Not all EU countries have negotiations and not for all industries, only the unionized ones, otherwise there's nothing to negociate with individuals and you can just let them go whenever you want to (most of the time).

Bitpanda in Austria instantly cut employees off once the layoffs were announced and escorted them out on the same day. It's legal and standard M.O. for most big tech companies when they let people go. You still get your legally required notice period, but you'll have to take it at home, not in the office.

It depends on the company, how vulnerable it considers its IP against potential sabotage from disgruntled employees, and since tech workers tend to be pretty skilled at the company's internal tech, most companies aren't taking their chances and immediately lock all your accounts and escort you out. All legal.

Those weeks of negotiations you're talking about mostly apply to old-school, factory style, unionized jobs at established conglomerates where employees don't have so much leverage for sabotage, and can't just be let go without heavy union pushback, but that rarely applies to tech workers who don't enjoy such protections because they've mostly seen a bull market where they didn't need/want it.

>Somehow, regulators are fine here with interpersonal discussion — including through electronic channels — still happening up to the last day of employment.

For most tech jobs, those communications once you've been let go, will have to happen outside of the company's internal network, i.e. using your personal email from home.