Programming

I'm not in Europe, but I am in a country with strong employee rights.

Even if I was a contractor, I would still have all the rights of a salaried employee. Employee rights generally cannot be taken away. For example I just straight up am not allowed to work more than five hours without a (paid) meal break. And my employer has to contribute to my retirement fund. They have to pay my federal income tax on my behalf (otherwise my boss goes to jail for tax evasion...). They can only terminate my contract with a valid reason - the government maintains a list of reasons, and they have to take reasonable steps to try to keep me employed (there's a requirements list for that too), and they have to give me fair notice (or severance pay). None of that can be taken away just because I signed a contract. But a lot of it doesn't apply if, for example, I only work there for two weeks or if I'm hired for 20 minutes to deliver a pizza (uber eats/etc).

(Strictly speaking... I can sign a contract taking away my rights, but the contract has to replace them with more favourable conditions for the worker... otherwise the contract is invalid and might as well not exist. For example I've signed a contract stating I have no sick pay or holiday pay... but in exchange they pay me for both, trusting me to set aside the money so I can afford holidays/unpaid sick leave (I put the money in a savings account that earns 6% interest))

I'm pretty sure it's similar in the US? Contractors do have full employee rights if they have an employee-like relationship - it's just US employees don't have many rights to start with.