With universities, my argument for public funding is that it theoretically makes higher education accessible to people actually interested in the subjects, instead of people who can afford it and go for the prestige of it. I feel that elsewhere, big name universities serve more as a platform for networking rather than actual educational institutions; here, I do not even know which universities are more or less prestigious. A degree is a degree.
In case of education, young student typically don’t earn enough to pay income tax, if they have any salary or wages at all. To them, it’s free. I now pay for them through my taxes and I am happy to because I was in their position and if uni wouldn’t have been so cheap, I could not have attended. It’s not free for the overall society, but it is free for those who use it.
Same for healthcare. We all pay but when you need heavy surgery or long-term care that would cost tens hundreds of thousands of euros, it’s close enough to free as to not make you bankrupt. Again, free-ish for those who need it.
On average it’s much more nuanced, though. Comparing at one given level of service, public services are actually good value for money.