>I have heard that the UK has a system that "shelves" criminal records after a certain number of years, and only employment in certain fields (like law enforcement, childcare, etc.) can view the records.
This is true but it depends on how long the sentence was as after a 4 year sentence you always have to tell an employer about the conviction. It's better than nothing as petty crime shouldn't have serious long term employment consequences but it seems like it doesn't do much for the people that might need it most.