Poway is a city, La Jolla is not. Poway has it’s own school district, La Jolla is part of the San Diego Unified School District.
The schools in Temecula were paid for by mello roos bonds, therefore the homeowners are paying for the schools over 30 years, not the developers. When people stop paying their mortgages, they also stop paying their property taxes and mello roos payments. Look for that to start becoming an issue (see Moreno Valley of the 1990’s).
The city doesn’t pay the salaries of the teachers so it doesn’t matter how big or strong their sales tax base is. Even so, when people’s homes are being foreclosed, they are not likely buying autos or shopping at the malls. If city revenues are down, it will start affecting police and fire (see Vallejo, CA potential bankruptcy). When a city starts cutting back on basic services, the population demographic starts to change rapidly. Teachers aren’t going to be attracted to “difficult” schools.