Because all those cars aren't carrying paying passengers. The rules are much stricter for vehicles that do. Similarly, the rules for private aircraft that don't carry paying passengers are much looser than those for commmercial aircraft that do. This has nothing to do with an "illusion of safety"; it's a simple principal-agent problem.
Are you advocating that private vehicles (cars, airplanes, whatever) that don't carry paying passengers should be held to the same rules as commercial vehicles that do?
> we don't care about changing things to save lives, because it'd be an inconvenience
No, it would be much more than an inconvenience: it would be a drastic increase in the power of governments that are already too powerful. Who is going to mandate all these things? Who is going to decide what counts as a proper breathalyzer, proper reckless driving detector, etc.? If you think a government regulatory agency can be trusted to make those decisions responsibly and not get captured by the industry, I have some oceanfront property in Montana I'd like to sell you. I don't want some regulator mandating such "features" in my own car. I'll take responsibility for safe driving on myself, thank you.
The question that should be asked is, why do we allow such power to regulatory agencies for commercial vehicles? After all, as someone else commented upthread, a regulatory agency that was protecting people's interests shouldn't have needed a fatal accident to convince them to impose stricter requirements; so the regulatory agency is not a perfect solution here either. And the answer is, as I said above, that there's a principal-agent problem in that case that doesn't exist for personal vehicles, and nobody has come up with a better way to address it. But there might well be one that we just haven't figured out yet.