I grew up in the UK, and went to public schools there (comprehensives, no grammar schools etc).
I've lived in Seattle, Philadelphia and now near Santa Fe. I've raised 3 children through public and a tiny bit of private schooling.
The good US education which my children received in suburban Phila. was very, very good. It wasn't really the education I had dreamed of them having, and it certainly wasn't the education that I received. It was different from both, but still excellent. My two daughters enjoyed school a lot, which coming from the UK in the 1970s is quite a big deal all by itself. My son, less so, but even he (now 32) finds many good parts to look back on. The education paid less attention to the rote learning I experienced, and lots more attention to collaborative learning, integrated curricula (crossing subject domains, for example), and individual student empowerment. So yeah, my kinds don't know how a wheatstone bridge operates (I'm not even sure they know how an electrical switch operates). But I am absolutely confident that they are at least as well, if not better equipped for the world they are now adults in than they would have been if they had experienced the education I received in the UK.
This is certainly not true across the US. But it was true in a very affluent, extremely well-funded school district, and that by itself, IMO, invalidates your claim.