I spent 40 years fixing things for people who wanted it done day BEFORE yesterday. When your customers lose a million bucks an hour when their machines are down, they don't mind sharing their stress. My standard reply when they asked me more than once "how soon?" eventually became "A lot sooner if you just stay in your office and let me concentrate on the job". I got cranky when I got old.Ah yes - but when mechanic leaves that job , he GETS to take his stuff with him!!!
The other dude simply consumed his money in the betterment of his students.
Everyone should teach for a week! Then again - everyone should turn a wrench with people who want their car fixed yesterday for free too!