That's not my experience (suburban DC). Overall, I'd guess closer to 1/5 or 1/10 do seasonal treatments. In wealthier subdivisions ($800k+ homes, which isn't unusual here), I'd guess half or more have regular lawn service including chemical treatments. In more middle-class areas, the number of professional treatments drops off considerably, but the residents still do a substantial amount of fertilizing on their own.
The highly visible actions of a few who have the time to take those actions (or pay for those actions) is not representative of the rest of us.