I've read an article about Chinese culture of "good enough". That many apartments fall apart right after they're built because if you do 80% of the job then that's pretty much considered "done".

Doing it correctly or completely isn't part of the contract.

A more apt idiom is "if you pay peanuts, you get monkeys." [0]

[0] https://idioms.thefreedictionary.com/if+you+pay+peanuts%2C+y...

There are two similar sayings that spring to mind:

一分钱，一分货 which means you get the equivalent in goods of what you pay in price, and

好货不便宜，便宜无好货 which means good products aren't cheap and cheap products aren't good.