I pay to have my car serviced... but I don't employ a full-time mechanic.

In this day and age, how often do you actually need to have your car serviced? And there is no shortage of places that will do it for you in a few hours.

Similarly, if money were no real object within reason, I'm not sure what I would really need done on a day-to-basis that I couldn't just order or contract for pretty easily.

You clearly don't have enough cars. Once you get enough cars, especially if any of them are classic cars you actually want to drive occasionally and want to be in a driveable condition, you might want to have a full time mechanic.