Why do we have 3 different credit scores?

Question

Experian, equifax, and transUnion.

Answer 1

It's the same reason why there are multiple burger joints, department stores, and airlines.  More than one company thought it'd be a good idea to provide that service.

Not every business uses all three reports, or report to all three agencies.  For example, auto lenders don't often use Trans Union.

BTW - there are more than just three consumer reporting agencies.

Answer 2

My best guess would be redundancy, to make sure everything is okay and accurate.  For example. If two agencies report 400 level scores and one reports 600, you know something is going wrong.