it's sort of simple really.
Obviously, older/higher miles = much cheaper up front. newer/low miles = spend a lot more up front.
Now, in the more $ up front scenario, you will 100% be spending the "more $" no matter what, because it costs more to purchase. However, buying newer does NOT inherently mean you will not also spend additional $ on repairs.
The 2nd scenario, where you buy an older one for less, is more of a gamble as you may, or may not, spend the same $ over the same odometer or vehicle age as if buying a more expensive vehicle.
There are pros and cons. Some people do not like to roll the dice on that but they are also fooling themselves to think that newer absolutely = less repairs or farther out into the future.
Odds are though that the longer the duration or the miles, it all works out more similarly. Meaning, if you and I both buy a rover today, but one has 75,000 on it and the other is 0 miles. I'll spend $70k now and you'll spend half that, or less. Over the next 10 years, will yours cost $35k in actual repairs?
Over the first 5 years of time, what can the bulk your $35k not spent on the vehicle do for you in other ways? It could start a small business, pay off expensive debt, be invested, CD's, take some massive trips while still healthy enough to enjoy them, etc.
Lot's of good reasons to try the older/cheaper route but that's where taking time to find a well maintained version comes into more importance.
About that miles thing, no, there are simply very low mileage drivers, high ones, and the type of driving matters more than the actual miles. For example, the person who starts the vehicle 4x / day for going to work, then lunch and home driving not far enough for a 100% engine warming and oil cycle, is doing more wear in some ways than me hopping in today and driving to the other coast, mostly just rolling at 70 mph for hundreds of miles per start up and all cycles are 100% so the vehicle is much happier.
It depends on how a person treats the vehicle too. Why do my brake rotors last over 50,000 miles...., my tires 65,000 but some other dudes are clueless about theirs running out in 15k... Well, I bet their seat leather looks like crap too and mine is fine.
Another example, I have a car with 112,000 miles, I might put on 750/ week but 500 of that was only 2 start ups and no stops in towns, etc. Just nice easy highways. The car looks practically new inside and mechanically.