Agreed. There's a lot of 'magic' that goes into running a quality recursive resolver, least of which is eDNS0 and EDNS Client Subnet - which intentionally returns different answers based on the requester's source IP -- in most cases for the most-optimal CDN location to be returned.

Test with:

dig @ns1.google.com www.google.es +subnet=193.8.172.75/24

dig @ns1.google.com www.google.es +subnet=157.88.0.0/16

Note how you get different IPs returned.

Here's a pretty clear demo of different results around the world: https://wheresitup.com/demo/results/5ef1403cb8e31e3fb3298503