My gas company and electric company are subsidiaries of the same company, and they use identical (read: equally terrible) websites with the same payment gateway. One of them lets me use a credit card and the other makes me pay from a bank account. ¯\_(ツ)_/¯

My landlord charges a flat fee for just using their online portal and my checking account. There's another 3% fee for using a card.

That's barbaric! But I guess it's understandable. Credit card companies and ISPs charge your landlord for providing their services, so he passes on the convenience costs to you rather than the people who have more time than money, and can shove an envelope fill of cash under his door.