> Why are you not paying enough to get them?

Because they’re not competent?

I pay my senior 30% above what he asked, he still doesn’t want to test all edge cases and lets slip many things because he wants us to hire a tester.

Actually competent people are paid surprisingly little, because then they struggle to increase their wage.

I don't think this is true... I've worked with excellent engineers and aside from a couple at the very, very beginning of their career (~2009/2010 no less when the economy was terrible) they were very well paid.