Background Checks

I am wondering,since all employer's,and perspective employer's are doing background checks on people sho are seeking employment or are employed by them,how many law's are they actually breaking? For one it's illegal for them to ask your b-day date,which i'm sure would come up.At one time I thought that they couldn't ask about arrest record's, which they now are. What about credit checks? If I'm applying for a construction job,what's my credit got to do with anything? So if a person apply's for a job, and they run a background check, and they find all kind's of thing's in your life history that they don't like,and you don't get the much needed job,cause you can't pay your bill's on time. Is there any place a person can go to get a free background check on themselve's to see why they weren't hired? Doe's the employer have to tell you that's why you weren't hired? I am wondering because I am over 50 and can't seem to get a job for the life of me, and am thinking it's because they are finding out how old I an through these checks. Is anyone alse having these problem's,or think that these checks should be illegal? Just happy to be a American!!!