There are ten of thousand companies out there, if you no tell,how employer will know? There is no centralised employment data like ccris or ctos

Background check is important for those sensitive position, or high post, like banking (handle client's million of worth transaction each day, even ordinary bank cashier also handled quite a lot of money each day), or crucial position that can assess/process company confidential info.

Other normal position, there won't be too strict background check one.