I think the widespread use of chat clients and services like slack in large companies has changed this norm.
There was a time where it would be unprofessional, but now its a solution to the communication flaw inherent in written messages. Conveying emotion.
My uncle who was in prison told me he voted against this last time because he believes if they have to pay prisoners comparable wages, they'll just give the work to contractors they are related to and charge the state.
He also told me that they can give 10 guys cleaning jobs, which gets them some spending money, time out of the cell, and extra perks when they would hire 1 outsider for that cost and have to deny access to that area while they work.
I've never been in prison, so I dont really know, but he and his old cell mate both expressed that the intent was good but the reality would be a negative for prisoners.