Don't know what the law is like in most states in the US but in the EU if the employee has been with the company for longer than 6 months it wouldn't even be legal to fire with 0 notice & no severance - generally companies wants you out asap but continue paying your salary for the minimums require by law. In my experience at least 2 weeks and more commonly 1+ months (I've seen people get 3 months, that have worked at the company for several years).
This of course doesn't apply if the employee did something like outright breaking the law or the terms of their contract (rare).
I think it goes without saying that the EU is different.
Here in Germany, in fact things are problematic in the other direction. For the last 2 hires I made, their previous company forced them to work through their 3 month notice period.
It's unreasonable for the company to want you to stick around for 3 months before you switch jobs, but it's not unreasonable to ask a company to let an employee who has been with them for years 3 months' (notice or severance) before they fire them (as the power balance is not equal - the employee is supposedly dependent on that salary for their livelihood and not everyone can instantly land a new job after being laid off).
Overall even as a business owner myself I prefer the pro-employee German system over the free-for-all American one.
That is not typical nor the norm.
Most companies have established PiP policies, and severance even in the cases of "for cause" terminations (though that is rarer)
"Fire with 0 day notice and no severance" is more likely to be found at startups, and/or small owner led companies with no real policies, or HR Depts.