Why does an ipad mini cost more

It doesn't cost more or less. It costs different depending on configuration.

Price depends on features. A Wi-Fi only iPad Mini 5 with 64GB of storage costs less than a Wi-Fi + Cellular regular iPad with 128GB of storage.

See here: https://www.apple.com/ipad/compare/?device1=ipad-pro-12-9&device2=ipad-mini&device3=ipad-8th-gen

For example I have a 6th gen ipad and one reason it is(was) less expensive is that it does not have a laminated screen like other models. The processor, how much memory, all that contribute to the price point that Apple sets

If you’ll forgive the pun, you’re comparing Apples and Oranges.

Different model, different capabilities, different price.

and the point to your question is?