Can I ask my boss why the workers with no previous experience are getting paid more?

Yes you can my dear.
'Cause the new employee with no experiences tend to be more loyal. When they are interviewed and ask why they should hire him/her, and they answered that they are willing to work with all that they can and they are flexible with the time and passionate with that craft or field, then the company most likely is going to think that they are worth getting paid more. They will think also how much more if they are focus and driven individual.