(which to be fair, is indeed more convenient than paying it in-person.)
1) I object to being charged to give someone money. If you tell me I owe you $90 and that you accept this list of methods to pay and I go to use one of those methods and you reply "oh to use that method I will charge you an extra $3.95," I am going to use the method that costs me an extra $0 because I already agreed to give you $90; you can work out how to collect that $90 in a way that only costs me the $90 I owe you.
2) It is an outdated fee. When it first started, electronic payments were new, novel, and cost actual money to put into a workflow. Now, physically handling checks and cash often have more cost to the merchant than paying electronically because the cost and logistics of electronic payments have been so streamlined. This fee has turned into a cash grab.
(That first point is why I still use paper checks. My apartment complex charges almost $50 to pay rent with a credit card and $10 to use a debit card. But walking the check three minutes from my front door to the night drop the day I get paid is entirely free since my credit union gives me a box of checks every year and I go through far fewer than one box per year. If my apartment complex finds that taking paper checks costs them money but electronic payments don't, they can adjust their pricing to reflect that.)
Of course apartments charge high fees for rent - they want to ensure they collect the full amount of their monthly rent according to the contract. A $50 fee on say 1000 dollar rent is 5%, ensuring they cover whatever Visa is going to charge them on the transaction. And if they get a little extra income for themselves - then all the better for then as you got some convenience out of it by not having to write a check!
Though presumably that's $50 a month.. So perhaps not.
I won’t pay extra convenience fees just for online ACH. I’ll just use my bank’s free bill pay service to mail them a check and they can deal with having to deposit paper.