How do you deploy manned fighters against an aircraft you can’t detect?

Detect and target aren’t the same thing. There’s various Air Defense platforms that can detect stealth air craft at 20-30ish kilometers but they lack the resolution necessary to target them.

I can buy thousands of rockets for the cost of a single F22 or F16.

Annnd were back to the Air Defense platforms being hideously expensive. Literally no one can afford enough of them to cover more than a tiny fraction of their air space.

Forget “thousands” of missiles any country larger than a Lichtenstein would to need to buy millions of them along with enough Ground Detection and Launch Stations to cover their entire border. Utterly and totally unaffordable.