Well, if the limit is 100 km/h and people still drive 120 km/h, then it's only their fault that they get fined. Limits are limits, you are supposed to respect them.

The situation would be different if, for instance, those limits would be obscured or appeared suddenly, and you'd have police forces enforcing them there on purpose. I've heard of cases like that.

Did anyone actually ask the people who put the limits about their reasoning though? Maybe this is the value that came out of simulations. Maybe it's a part of an environmental strategy (going 120 km/h uses much more fuel than 100 km/h and thus leads to greater emissions). But maybe the simulations were wrong. I'm sure that there are proper channels one could use to dispute the limits. But just disregarding them because they 'look wrong' is pure hubris.

They look wrong because we have 130 Km/h on a very large chunk of that road and the last bit (the widest) then becomes 100. It basically suckers in everybody driving there the first time so it's not as if it is clear to most drivers what the limit there should be. Speed limits should make sense, not be arbitrary.

That they change them frequently doesn't help either.

Ok, fair enough. That sounds more like purposeful extracting money from drivers than ensuring safety and optimal flow.