For one thing, those laws (similar laws do exist in the USA, Canada and elsewhere) do not protect hobbies and people following a hobby.
I agree - but that's not the entirety of what you originally said.
I also agree that an employer who wants to get rid of you - even with protections in place - will probably find a way. They can check timekeeping down to the second, phone/internet usage etc, etc. However, from a utilitarian/economic point-of-view why would they sack a valuable employee?
I still find it hard to imagine a work environment that is so red in tooth and claw that the employees are trying to take each other out but while the employer doesn't just look at the bottom line to see who is a useful employee.
Equally, if there were two equal performers and one was put aside based on an unusual hobby then that would be unfortunate.
I should say that as an academic physicist my workplace is very geek friendly. I took the morning off to see The Force Awakens on its first day at the cinema and there I met a colleague who had taken his entire research group to the same showing.