It doesn’t, it’s just not designed the way you want.
Perhaps you are not familiar with filters...have been filtering by voltage range, current limit ohms, cut tape, in stock, active, ect for years with no problem. Now it is failing to properly do so. If we want to see other options, like reels, bags, busloads, whatever, then we will select those & expect to see them.
If you select to show only 100 ohm and 488 ohm resistors, you should not see 345 ohm resistors appear.
Of course I know how filters work, as I use them on a daily basis. What surprises me is how confidently condescending you are, despite continuing to demonstrate that
your understanding is rather weak.
You keep insisting it's showing items that do not meet the criteria,
but it's not. I'll come back to this later.
You don’t seem to know what a SKU is You don't seem to be investigating ...there are only digkey numbers and manufacturer numbers listed & where does it say they are limiting anything regarding sku's? What limits digi from selling a LM947AA-XP3-2N and also littlebug from selling a LM947AA-XP3-2N (from who knows where) ...nothing that is apparent.
Aaaand you just confirmed that you do NOT know what a SKU is! "LM947AA-XP3-2N" is the model number, aka (manufacturer) part number, NOT the SKU. The SKU (short for "stock keeping unit") is what DK calls the "DK part number". It is common for there to exist multiple SKUs for the same part number, due to packaging options and the like.
Let's leave aside electronics components for a quick second and pretend we are talking about pencils. Suppose the pencil's model number is "123HB-Y", for pencil style 123 with HB lead, painted yellow. And the manufacturer sells them in blister packs of 6, boxes of 12, and boxes of 100. The manufacturer assigns each a SKU: "123HB-Y-6B", "123HB-Y-12", and "123HB-Y-100", respectively. A retailer can order them from the manufacturer only in those package sizes, by ordering with the manufacturer's SKU. They can sell them however they want, so suppose the retailer also wants to sell individual pencils, so they create four retailer SKUs. Let's call them "PencilCo 123HB-Y-1", "PencilCo 123HB-Y-6", "PencilCo 123HB-Y-12", and "PencilCo 123HB-Y-100". When you order a "PencilCo 123HB-Y-1" (i.e. qty 1), you don't care whether the retailer obtained it from a manufacturer pack of 6, 12, or 100, because once removed from the packaging, a "123HB-Y" pencil is the same. Make sense so far? Do you see how the model number, the manufacturer SKU, and the retailer SKU are different things? Additionally, we could also say that the 123HB-Y is a "yellow HB pencil", because in many situations, the manufacturer doesn't matter, as long as the pencil is yellow and has HB lead.
FWIW, the UPC barcode is the retail industry's attempt at unifying manufacturer SKUs and retailer SKUs.
Back to component filtering: In the past, DK always treated each package size as its own SKU. But as the buyer, ultimately what you're after is the model number (i.e. manufacturer part number). In the past, this led to DK results listing many SKUs for the same manufacturer part number unless you went and filtered out the packaging you didn't want. Now, they concatenate it down to the manufacturer part number — it's one line item now, not 3, for the typical SMD part available in whole reel, cut tape, and digireel. They just show you the available packaging
within the line item. When you filter for parts (manufacturer part numbers) that are available as cut tape, it will eliminate parts that are
not available as cut tape, and shows you only the ones that are,
even if they have other available packaging as well. But the list of parts does indeed only contain parts that are available as cut tape. You literally can just ignore the fact that they display the availability of your part in other packaging. (As already said, the part of your criticism that I agree with is that displaying it isn't that useful, and consumes space. But it's NOT showing you parts that do not exist as cut tape, as you keep insisting.) If you have filtered by cut tape, and you choose one of the parts in the list, you WILL be able to order it as cut tape. And that's what it's all about.
When it comes to third-party, DK does not appear to allow multiple suppliers for the same DK SKU (DK part number) the way Amazon does. So if DK has LM947AA-XP3-2N sourced from the manufacturer, and so does littlebug sourced from wherever, they may share the same manufacturer part number, but they won't have the same DK SKU, so when you go to order, and you filter to not include marketplace vendors, you cannot get the littlebug stock by mistake. DK doesn't group third-party stock into a manufacturer part number the way they do for packaging alternates.
Nor could they, since manufacturer part numbers aren't globally unique. For example, a Keystone Electronics "3534" is a PCB connector, while a Pomona Electronics "3534" is a BNC adapter. So you can't just say "oh, the manufacturer part number is 3534 so they are the same thing". They're unique only
within a manufacturer. DK treats a third-party supplier as a different manufacturer, when it comes to grouping.
As another example of the layout mess...where they need to have some width, they don't provide it & force the listing to waste 6 lines. Yet where they don't need the width they give 2x or more than what is needed, just to waste screen space.
You already said this yesterday, and I already responded yesterday: clearly, the column widths are being automatically sized to fit the column name. Clearly NOT set by hand, since the widths are being set to µPx resolution, which no human would do.