You can earn 5%+ risk free now, so borrowing at 5% to 7% to buy a car is just good business. There is no early repayment penalty, so at the least, you get to keep access to liquid funds for a negligible cost, or you can use your invest your money to earn a better return elsewhere.

Sure, but doing those sorts of balances are more hassle and pain than they tend to be worth to me (and it still involves risk). Others who don't find such things unpleasant certainly have a different result in their cost/benefit calculations.

If you're comparing to paying cash for a purchase you were going to make anyway. If you're comparing borrowing at a break-even rate to buy a new car vs paying cash for a lightly used car, borrowing is not what I'd describe as good business.

You can get some pretty great interest rates on auto loans at certain times, due to promotions or unusually low fed rates. I could have bought my car with cash but happily took a loan with a sub 2.5% interest rate.

Aside from low rates though I agree that there's not much point in getting a loan if you're able to comfortabely buy the car with cash, although many/most car buyers don't have that kind of financial flexibility.