Recent iphone models have “easily” removable back glass, and it’s actually the main entrypoint for replacing the battery, lowering costs due lower risk of a broken screen (see new google pixels with screens that almost always break on removal)

After this, apple also lowered the cost of most repairs, including on models that don’t get the new replaceable back. the non applecare cost for a battery replacement ranges from 80-100 dollars roughly. which is comparable to the cost of a replacement with even a generic battery from a 3rd party shop.