This has been true for a long time. I think it is still safe to assume googlers are not stupid, so there must be a reason for that. My guesses, in order of decreasing confidence:
(by far) 1) globally seen, the results given are best for the general population
2) search/ad revenue from "still-google-users" vs. switchers is in a sweet spot
3) ???
I'd bet on 1), since google was historically nerd-focused, but that changed long ago, and including inertia and stuff, they have probably realized by now that the crowd of "i know what i want, just give me the link" is not driving key performance indicators.
(by far) 1) globally seen, the results given are best for the general population
2) search/ad revenue from "still-google-users" vs. switchers is in a sweet spot
3) ???
I'd bet on 1), since google was historically nerd-focused, but that changed long ago, and including inertia and stuff, they have probably realized by now that the crowd of "i know what i want, just give me the link" is not driving key performance indicators.