I am looking for an idiom in English, if it exists.
In Czech it goes like "Z ciziho krev netece", literally "Someone else's property never bleeds" which was probably originally meant to describe the situation that you don't care that much if you damage other people's stuff as it's their problem (at least unless they catch you or are your friends and you borrowed something).
It has been used in various meaning since, though - mostly related to money lending or funding.
For my particular purpose the context is that of university funding - the lab leaders don't invest their own money in the research which allows them to be a bit more careless when it comes to spending.