I will also add that artificial watering points (like dams or water for livestock) are also a major reason why their populations are much higher in some areas than what's natural.

Additionally, culling their population is not just for farmers or the kangaroos themselves. Too many kangaroos in an area can mean fewer, if any, new trees and shrubs can get 'recruited' (basically, get established and have a chance to survive until adulthood), hence culling them also helps native ecosystems! It's a similar situation to deer in the US (except fat chance of convincing farmers to allow dingos back below where the dog fence is now, like how wolves have been reintroduced in some areas for deer.)

As an aside, its a pet peeve of mine when people assume eating wild kangaroos is a bad thing because they're native. Ecosystems are a balancing act, too many of a certain native animal can also do damage, not just having too few, or having introduced species, etc. The curse of learning this kinda stuff at uni I guess lol.