There is a general problem that a commons transitions from abundant to tragic as demand grows. At what point do you introduce some kind of centralized regulation (eg, property rights)? How do you do that?

But space is nowhere near that point. Not worrying about Kessler syndrome is the right answer. And if it were going to be a problem in the foreseeable future, there are very few users of space, so they could easily negotiate a solution. If you expect that in the future every city of a million people will be sovereign with its own space program, then there is more of a tragic commons, but in that scenario space is the least of your problems.