In EU, there are multiple ways to fire someone:
Few examples:
1. Increase the "experimental time period" in the contract - (The default period it's not enough to understand someone's behavior/atittude as a worker. You need to give them time to adjust and understand if that's the type of person you need, what lack in most companies it's a strong structure in terms of personal)
2. Force to resign - There are also multiple ways, by the law and giving an example let's say you have a business and you caught a worker stealing (money or redirecting clients for example), if you understand the system and the applying laws you can force the to resign based on proof that you know it will stand in court (in case it will be needed). This way you just chat with them "look this happens, we know, we have video proof and this video is registered and it will be approved in court so let's not waste our time and resign your contract, also know in court as "just cause""
There are more but these two are the most common ones, the law around here have a good protections, but i'ts made (in my perspective) for big corporations to know how to handle this situations in large scale, as everything it's a process and companies always have their own ways to do this.
Note: The protections around here depend on the type of work you do, for example in my cleaning companies the law says services like cleanings can have routational shifts what will affect how the contract for that type of service is done in terms of shifts, working on weekends etc and most people want weekends off and they think the law protects them and in this particular case it's not how it works (just a particular example to make you understand what I'm trying to explain and how it works and this can be used as a "just cause" to fire someone who does not frame into that position)