It's a bit like when a local airline here once spent millions in branding research, and started calling their passengers 'customers'. It was really odd to be sitting at the airport and hear the call "XYZ Airline would like to advise all customers on flight 123 that their aircraft is ready for boarding through gate 6"...
I always think of the term 'passenger' in more romantic terms, whereas 'customer' seems more mundane. FWIW, the airline seems to have dropped that branding now, and have reverted to calling their, ahem, passengers as 'passengers'.
Every single time I am referred to by that name over the PA it weirds me out. Maybe if this was a private system, but for public transport? Customer is just the wrong word.
Yes, these users are human beings but outside of academic settings, who ever calls someone a "human?"
User is an established term for a person in software, just like customer is a term for a person in commerce, or patient in hospitals. These are all humans and nobody is losing sight of that. No need to rebel against that just to express certain moral high ground.