The Mage's Guild was the hub for all practitioners of magic—especially those interested in keeping up with the latest news in regards to magic and its developments. That was to say, only birds of the same feather flock together. The Mage's neighbor next door wasn't going to be interested in the recent spell matrix found in an ancient tomb unless that Spell was something that they could use and even more so, afford to have someone use.
Not everyone was capable of paying Mages for their often expensive services—and even then, who had the need to make a [ Water Spike ] when you were a Baker looking for a solution to prevent rats in their shop?
And so, Mages were also forced to do other services, some that may have been 'menial'.