There is, however, a "ban the box" movement in a plurality of states, banning employers from asking potential employees about a criminal record.
With the internet documenting all public information, however, it's normally trivial for an employer to do a little research and find the employee's record.
Typically, an employer can run a criminal background check in a "ban the box" jurisdiction, but only later in the process (for example: after completing interviews and provisionally deciding this is someone you'd like to hire). There may also be other rules in place about how you can use information from the background check, and what you have to do if you decide to revoke the offer of employment based on the result of the check.
You just can't ask on the application form. You can ask later on in the process though. The idea is to give people with criminal records at least a fighting chance of getting interviews.
Arrest doesn't imply conviction or even the low bar for indictment. For instance SWAT protocol is to cuff literally everybody else possible on the scene for one and then assess and release after the scene is secured. One would have to be completely stupid and paranoid to think you shouldn't hire someone because they were in a bank robbery turned hostage situation as a victim.