Those regulations are designed with the knowledge that 100% compliance is impossible, so a safety buffer is designed in that ensures people are kept as safe as possible even within an imperfect regulatory compliance regime. Those limits are a target, and plants will likely exceed them slightly from time to time. That might not be caught for months, and keeping them at such low levels means the plants can have reasonable time to return to compliance without shutting everything down.
That's over and above the possibility of catastrophic disasters, which are covered through other regulations.
Some regulations are bad, sure, but there's generally a ton of thinking and precedence behind those related to safety.
When it comes to regulations, there are cultural differences in compliance. In places like Germany and Scandinavia, I'm pretty sure that such over-provisioning through regulation is overkill.
Anyway, a lot of old nuclear plants are still in use, and the total number of deaths is extremely low. We would have to lower safety standards quite a lot for the average safety of the new plants to be lower than the average of the pre-existing ones.
That's over and above the possibility of catastrophic disasters, which are covered through other regulations.
Some regulations are bad, sure, but there's generally a ton of thinking and precedence behind those related to safety.