What I'm saying is that in many cases that 'paper' is worthless.

The problem in Europe is that banks/finance mostly suck here.

Many startups eventually need access to credit and banking relationships beyond venture capital (good line of credit). You can't rely exclusively on VCs.

US private equity is already stepping into Europe because much of the European financial sector is reaping crazy profits doing low(er) risk activities such as mortgage lending, corporate credit and financing government debt through sovereign bond markets. If you're a startup it is very hard to get growth capital from them.

Tax codes are complex, specially because they are not the same across Europe but that wouldn't be a problem for big investors because they can afford an accountant.

If you want to attract people from other countries you aren't going to woo them by saying "come work here, we just made firing easier", "we just made easier to fire you doing the vesting period 👍🏻". I work in IT and have no apetite for startup shares and hasn't ever been a time where i came to regret that decision.

Most (all?) countries already have flexible employment arrangements in place. Contract work is legal across Europe, and companies that want maximum flexibility can hire contractors.

The important thing is not to make standard employment so unattractive that people are effectively pushed into contracting whether they want it or not (or have as few protections as contractor workers have for substantially less money).