I assume he meant coaching full time would not pay the bills for living. My kids elementary school doesn't have their own teams/coeaches, everything is managed through different NGO/non-profit which has contracts to use gyms in various schools. The yearly fee for being member of a sport club varies between 100-250EUR which certainly is not enough to pay the coaches full time.
This entire concept doesn't exist in much of the world. The incredible prevalence of intramural sports, and the seriousness of it, at all kinds of age groups is a very US phenomenon. Let alone random neighborhood people coaching teams.
In most of the world it's more club-based rather than school-based, and that's quite different.