Try counting number of DNS queries for all lookups every day. The software I wrote for myself does this and I can attest that sites using AWS nameservers in almost all cases require more queries than others, including those using similar managed DNS services. The number, which does not include queries to the root can be quite high, e.g., eight. No matter how fast the response times, that delay adds up.

root.zone data is reasonably static. Having a local copy of this data, resolution can be done in two queries: 1. tld ns 2. auth ns, which is the case for many, many www domainnames (the majority, perhaps), or even one query (I think some .mil domains used to be a well-known example). As a user, I view every added query as an additional cost.

It is possible to minimize queries via other means that are under user control and do not rely on third parties.

Running a root locally. Custom stub resolvers with tld ns IPs compiled in. Storing RRs for common nameservers in local zone. Storing DNS data in bulk for important sites that will be revisited, copying to HOSTS and updating the data periodically. I have been using techniques like these for many years. And, it is getting easier every year as more bulk DNS data is available, e.g., internet scans of DNS, TCP DNS services that accept pipelined queries, etc. (If I am not mistaken, the author of the "qname minimisation" draft also was the one with the "DNS looking glass" idea.)

https://tools.ietf.org/html/draft-ietf-dnsop-qname-minimisat...

Despite usual mailing list/forum comment/blog memes and mantras, if one surveys all websites (not just popular ones), DNS data is mostly static. That provides great opportunities for speedups by avoiding querying ICANN DNS for the same data 24/7/365. Cue Schopenhauer quote about truth. Someday maybe we will see an internet draft about "DNS minimization" for users.

Did AWS forums start requiring an account for read access?