People are skeptical that introducing the regulatory threshold has anything to do with the increasing public safety or accountability, and instead lifts the ladder up to stop others (or open-source models) catching up. This is a pointless, self-destructive endeavour in either case, as no other country is going to comply with these regulations and if anything will view them as an opportunity to help companies local to their jurisdiction (or their national government) to catch up.
The other problem is that asking why software should be different if it can affect someone's life or livelihood is quite a broad ask. Do you mean self-driving cars? Medical scanners? Diagnostic tests? I would imagine most people agree with you that this should be regulated. If you mean "it threatens my job and therefore must be stopped" then: welcome to software, automating away other people's jobs is our bread and butter.
The religious conflicts? 80 years war?
The invention of copyright (which does still restrict the right to print, it's just enforced with after-the-event prosecution if you print the wrong stuff)?
The invention of the modern nation state?
Government cannot regulate it.
Entities operating SaaS are in a much greyer area.