They tie up with local mechanical workshops. These workshops, readying car can varie based on their quality.
I recently booked from GoMechanic, they tied with "bookmycarservice" workshop. These guys checking lists, as mentioned is bad. The car was delivered with no proper cleaning itself. I could see sticky dirt with no proper cleaning.
One thing to notice is the review provided below is how valid or not, all are given good ratings, with same date with just 10mins of difference. How much valid review, I am not sure.
I would suggest you guys, when going to GoMechanic, try to ask, which workshop they will be servicing from. This is most important to valid quality of the workshop.
I had to contact 3 times so far after the service done. It is pretty delay and slow in terms of actions. GoMechanic, will just say, about contacting but no actions taken as reminder call or re call from service workshops.
DELAY DELAY DELAY!