People keep speaking of kill buttons, but electric cars don't have those and electric bicycles don't have either.
Kill buttons do not exists because people (marketing, politicians and legislation)
expect that "normal people" feel uneasy around them. This is the classical "do not remind about the bad things" concept.
Yes, I'm serious. It's a known issue that a lot of people do not use seat belts. It's a similar issue psychologically. Luckily, seat belts got into the legislation at the correct time slot, with some good sense for sane safety culture back then.
The designers for such systems
definitely want to design a product that is safe without an emergency stop switch. I would, too! I just know I cant't do it, hence the emergency stop switch exists (actually two of them symmetrically in my product, so that people don't need to waste time trying to remember which side it was...)
There's no problem with heavy machinery such as lathes, since deep down we think that a machinist is OK with all this, and doesn't need sugar coating the world around them.
But for general public, the "stupid people", as legislators and product managers erroneously think - the switch is a "disgrace" to their "safe product"; admitting that something could go wrong is not good for business value.
Accidents, on the other hand, are quickly forgotten. Unless there are stop switches, which are the problem because they remind you about the accidents all the time.
Let me give you an actual real-life example where this shows very well.
Until recently, a lot of old elevators, some hundred years old, were still in use here; now there has been a trend to upgrade them. These old elevators do not have inner doors. The safety issue here is of course obvious. Until about early 1980's, they were like this. This being said, all of these old things do have a simple safety feature:
A stop button!
It isn't a big red mushroom thing, but nevertheless a button which says "stop". It's not dramatic: it stops the elevator. If you push it accidentally, no harm done: press the floor button again and off we go.
Now, most of these old elevators have been upgraded (completely rebuilt and replaced with new stock elevators) to modern "safety standards". What this means, there are inner doors (and I'm sure controlling them involves 100000 pages of safety paperwork and 100000 lines of autogenerated and "formally verified" microcontroller code.)
But there is no STOP button! Total number of stop buttons I have seen in any modern elevator designed after year 2000: absolutely zero.
Now, the typical accident nowadays with these elevators goes like this:
1) You have a dog. Your dog is in leash. You walk inside the modern, "safe" elevator
2) Someone presses a button. Doors start to close slooooooooowly.
3) Your dog suddenly gets an idea to go outside.
4) You quickly push "open the doors" button, but you are late: the safety-certified MCU with its safety-certified and formally verified code is no longer registering inputs because that's not in the specification.
5) The doors continue closing, sloooowly. Everyone starts to freak out. The elevator starts moving slowly and steadily to keep up the ironic atmosphere of waiting your dog to be killed by the stuck leash between the inner doors.
6) People try to franctically push all switches and do everything they can. There is no way. Your dog is killed in a slow process.
The doors are fine, but the "safety sensors" are not up to task and do not prevent these accidents from happening. But, because everything is perfectly engineered to the rules, with millions of pages of safety standards completely followed, against all common sense, the STOP button has been legally removed from the elevators.
The bottom line:
The modern safety culture just totally sucks. It's as bloated and inefficient as modern software. (And, funnily, it often is based on a large piece of software. If anyone sees a problem with that, the typical solution is to double the amount of software to make it "redundant". Go figure.)