If wifi-enabled printers are a bad idea, I'm wondering what kind of printers (brand even perhaps) that secure companies use, such as banks or financial institutions. I would assume these printers don't even have the capability of wifi, that is they are ethernet-only. But searching around I haven't really found anything to start on ethernet-only printers with all the standard security features of secure printers (password protection, encryption, lack of hard drives, etc.).
Mostly they use multifunctional printers of major vendors (I worked for few and I installed printers in banks, government offices, police etc.). They have turned on every possible security features like HDD encryption, SSL communication, password/chip authentication, disabled USB ports etc. Sometimes even customized firmware. As "normal" installation took few minutes, at those places it usually took ten's of minutes. There is also special procedure of replacing old/faulty machine including formating and (multiple) rewriting data on HDD and then certified destruction of HDD.