The latest generations of gnss receivers have spoofing and jamming mitigation and detection features included with the chip, and multi-band rx technology to sync to more constellations simultaneously and do exactly what you’re talking about. Before then, the spoofing/jamming detection would likely need a software implementation after the receiver. There are different types of spoofing/jamming, all of which are detected and mitigated in different ways.

I don’t know the commercial aircraft industry standards for updating technology, but I wouldn’t be surprised if most commercial aircraft don’t have what you’re talking about.

It means for the first 20 years they spent all of their profit on expansion / R&D

Did you also get paid for the time you spent traveling?