What's the drawback of buying a new car with delivery miles?

I know that some new cars are advertised at a high discount with low mileage because dealers have to meet expected sales figures - but what is the real significance for the buyer?

My new car was delivered in bad condition - can I reject it?

I bought a new Jeep Renegade via Carwow. Firstly, it was driven to my home, from the dealer, which I have since noted is some 240 miles away. This was never discussed. Bad enough but it the actual mileage...

Should I choose a low mileage car over one with a higher mileage?

I’m looking at two Jaguar E-Paces, one 2018 with 70K and one 2019 with 40K. Should the difference in mileage urge me to purchase one over the other?