I’ve got 12,000 images on my iPhone with Download and Keep Originals and my iCloud Photo Library uses less than 35GB. New photos have actually gotten smaller thanks to HEIF. 4K videos though, yep, those are big. Mind, I expect those who know they take a lot of photos and videos would know to either spring for bigger storage (probably even 256 and 512GB) or offload the content. Doesn’t seem like 128GB would be sufficient for that.
Yes, Apple’s stingy with storage. However, situation’s a lot better now compared to the last few years with 16GB base. Iirc, 16GB was base storage from iPhone 4 through 6S (2010-2015, 6 generations). If they had been as stingy as before, we’d still have 32GB base on the iPhone 12.