Money is a big deal for ease-of-use and access. Tracking down a credit card and the necessary approvals to use it, even if the amount of money is no big deal, is a lot of friction for many people. Could be corporate red tape, could be that you don't have a credit card. Could be because you're in a country where financial sanctions prevent you from transacting with a foreign CA.

All of this friction would lead to many sites not using HTTPS because it's just too much of a hassle. And it's the visitors to those sites that suffer most.