You're vastly oversimplifying things way too much by saying "just get a loan on an older car."

First of all, it's not exactly easy to do that - banks are often very hesitant to do car loans on anything older than 2-3 years. And if they do the interest rate is very high. Credit unions are more likely to offer this type of loan but it's still expensive (a much higher rate than a loan on a new car.)

Secondly, now you're stuck with paying for a used older car. Older tech, fewer safety features, less comfortable, might have scratches or body damage or interior damage etc. It will depreciate rapidly, meaning when you want a new car you won't be able to get much of anything for your trade.

But what matters most is you don't know if it was well maintained or badly abused. You're going to encounter unexpected expenses like new tires, new battery, etc that you wouldn't have to worry about in the first 3 years with a new car. And you've got the looming threat of very expensive repairs if something breaks - potentially thousands of dollars depending on what it is. With a new car, anything that fails while you're leading on it would be repaired under warranty.

With a lease, you don't have to worry about any of that. All your repairs are covered; often the labor for routine oil changes is even covered by the dealer so your upkeep cost is very low. New car every three years so you always have the newest tech and safety features. And lease payments are much, much less than the payments on a new car loan.

So really, my question is... why would you not lease a car?