Is it a regional thing? Because I grew up in Southern California and lived there many years. Also lived in Arizona and northern California for a few years. Always shoes in the house everywhere I went and everyone I knew.
I definitely think it's regional. I think that it's more common in very dry climates like california/arizona. I mean honestly, my shoes are almost never visibly dirty when entering the house. It's not like there's mud everywhere in southern california. I wear shoes in the house all the time and my carpet looks fine. Until covid-19 I never thought twice about it.
I think you're right about the regional thing, although when you think about it wearing the shoes in the house is a pretty weird thing to do. Probably also not good for foot/ankle development given all the support most shoes give you.