They are tautological but not axioms

2+2=4 can be proven as a theorem of mathematics

Another example:

"Every effect has a cause"

Can you think of some way this could be tested?

Can you think of some way the human action claim can be tested?

A more familiar example:

"A binding minimum wage will result in higher unemployment than would otherwise have been the case"

Can you think of some way to test this?

You would have to apply and not apply the minimum wage to the same group of people at the same time (or perhaps you can find a large population of clones in identical circumstances).