Same here where ever my car goes for work i wait there till its done now! never use to untill what u read in amin.....
Only reason for this is a garage a few years ago that did some work, told me it would take a few hours as they were busy & to come back near the end of the day, so i left my car & went home (i always take a picture off my mileage when leaving it with garage) anyway came back to collect car & straight away noticed my fuel gauge had gone down by alot, they had only used my car to do 120miles in, lets just say i flipped at the manager, got the work done for FREE & they even payed to refill my car! only as i threatened them with the police & showed him i had evidence on my phone off my mileage when i dropped the car off.
But yeah because of the above my car never leaves my sight now