I would be curious if you could provide any examples for the issues you cite. They sound plausible to me, especially around peering disputes or in various Asia countries, but I wonder how in practice this looks in like a traceroute for the amount of added latency etc.

I would suspect some of non-optimized scenarios are eyeball network operator decisions on their networks that DNS providers and others do not have much control over. Like, Cloudflare resolves an IP that is closest to them, which is likely also the closest to the end user (and the eyeball ISP), but the eyeball ISP BGP path to that resolved IP takes a roundabout path because of their own BGP policy because $reasons.