Yes and no. The engineers certainly COULD design the different models to be physically limited and more difficult to hack, but that would come at increased cost of production, and the low end models are the least able to absorb any extra costs. Making four different models that are really identical hardware and software saves A TON of money in both design and manufacturing, and if that's enough saving to sell a 200MHz scope at a 50MHz price, then all the better. The company can still sell the scopes at the higher price, but what the buyer is paying for is the promise of performance, not the difference in hardware.
The plot thickens, even.
Imagine something challenging to manufacture such as a complex IC (a microprocessor). Processes are not perfect and you get a variable yeld (percentage of valid units). Also, maybe not all of the valid units offer maximum performance due to process variability. But if you sell the same component in several grades you can test which ones are the best and assign them to the higher class, selling the rest as the basic ones.
This happened years ago with Intel processors, for example. They sold several versions of the same processor, valid for different clock speeds. Let's simplify with two: 75 MHz and 100 MHz.
As far as I know both came from the same wafers. They tested the chips in order to select which ones were 100 MHz capable. But it got a bit more complicated
If they had produced, say, 100,000 processors and they had an order for 10,000 100 MHz units they would only test 10,000 of them for 100 MHz performance, not bothering about the rest. The 100 MHz test added to the total manufacturing costs and it was pointless to test units you were going to mark as 75 MHz for 100 MHz compatibility.
And it got yet more complicated
With time manufacturing process can improve. So, if at the beginning of the manufacturing period you get, say, a 70% yield with 10% capable of the highest performance, maybe in a year you improve the yield to 80% with, say, 50% or more of those 100 MHz capable. But if you are going to sell only 20% of those as the 100 MHz version, turns out many of the low end version units are actually 100 MHz capable. Overclocking was born
With these scopes the same could happen. These units at 200 MHz are not that challenging to manufacture. But for more complex equipment I wouldn't be surprised if hacked a low end version didn't work perfectly as a higher class model.
So, again, a professional customer who requires dependable measurements will need to pay for the high end model instead of hacking.