There's a world of difference between "this person has a track record of not paying their bills, so exercise caution before lending" and "this person was observed reading subversive literature, so don't let him leave the country".

I agree that pre-employment credit checks seem unhelpful for most lines of work (but consider: do you think a bank should be happy to employ a sysadmin with massive gambling debts?), but I have my doubts that every employer does them as you imply.