My take on on roos and dingoes.
Do they affect the roo population? Yes and no!
When kangaroos are mentioned it's often thought that they are all the same but it's like lumping whitetail, mule deer, blacktail, elk, moose and pronghorn all together and calling them "deer". There are a number of different species of kangaroo that inhabit different parts of the country. Then there are the wallabies, wallaroos and potoroos that are all part of the macropod group with the kangaroos. Mostly the larger species all get lumped in together as "Roos" and I will mostly just do the same for simplicity.
They are all part of the dingoes diet to some extent.
We have hugely altered our country by adding water points and good feed where there was historically very little. Roo numbers used to be kept in check by the drought cycle. Numbers would build over good seasons, they would migrate around the country chasing good conditions but when drought hit, they would perish by the thousands. Now with all the reliable water, it takes a big drought to kill off big numbers and the roo population is unnaturally high. The more coastal temperate regions have permanent natural water and feed so it's a little different to the rangeland country further inland. These areas have plenty of Roos and plenty of dingoes but there are localised effects of dingoes reducing numbers or moving Roos around the landscape.
We have also built the worlds longest fence (1500miles long) to keep dingoes from the more productive sheep country. https://en.m.wikipedia.org/wiki/Dingo_Fence
This also prevents some of the previous migration of Roos and emus. In general there are less Roos and more dingoes outside the fence than inside and this is often used as the evidence that dingoes control Roos. In reality there are a bunch of factors that cause the difference. The land outside the fence is marginal, arid country that supports less Roos, the fence stops the long distance migrations so numbers pile up against the fence and the farming/land management systems are different overall. There are also lots of dingoes inside the fence these days so the comparisons aren't that valid since dingoes are on both sides!
My experiences seem to tell me that dingoes do have an effect on roo populations but water and feed availability are much more important. I've trapped properties with high dingo numbers that also have seasonally high roo numbers - large 100000 acre properties can have tens of thousands of Roos at times while also having dozens? of dingoes.
Up in the tropical north there are thousands of agile wallabies despite a high dingo population.
Recently I trapped 19 dingoes from around a 1000 acre property surrounded by forested country in the temperate mountain area. From a single location I also counted 50 Roos bedded/feeding in the paddocks during daylight hours. There would have been twice that number that I couldn't see. Those dingo and roo numbers would both be considered excessive but the dingoes weren't having too much effect on the roo numbers.
It's such a huge topic but very interesting to delve into. We are beginning to have the apex predator debate in this country with dingoes and Roos being the two species most often talked about. Yellowstone is always raised as the example we should be following. The negative effects of that predator reintroduction are rarely mentioned by the "re-wilding" advocates though.