Question about Challenges

Hey quick question that I have been trying to figure out, how do I make challenges on basegame tracks and other people's tracks? Can I only make them on my own custom tracks?

you can't obviously you can't make 'em on other's it's their tracks.

What about base game tracks?

no you can only make challenges for your own tracks

Ok, thanks. Kind of weird though, I wonder why that's the case.

I can think of a few ideas, such as:
spam (annoying for validators [and players too ig])
it's someone else's track, it's their 'property'.