Also roads and other infrastructure; police, fire, and EMS; agencies like animal control, consumer protection, aging, and others. (Some of these are on the county rather than state level, but the counties usually follow the state's lead.) Also, even if you don't use public schools or universities, there are many ways that good school systems can improve the quality of life for residents who are not students or parents of students.
(EDIT: I'm not saying everyone, or even anyone, needs to or even should value these things. They're just the trade-offs for lower taxes that often are forgotten in day-to-day living. As I've mentioned before, I have friends who retired from Maryland to Florida who occasionally complain about road maintenance or zoning issues or something similar, and I remind them that's the trade-off they make for lower taxes. Also, they rub their winter weather in my face, and I rub their summer weather in theirs!
)