I don't think he's arguing that it's equivalent to charity, but that's it's part of building an equal-opportunity society. He's arguing that he benefitted from that society, much of which was funded by other people's taxes, and is happy, now that he has money, to pay taxes that keep it in existence for others.
My parents have a vaguely similar view. My dad lived for a few years when he was a kid from social-security disability payments that his father received; and he went to college on a CalGrants scholarship, which at the time covered you almost fully if you had good high-school grades and were attending in-state. He would've been in quite difficult circumstances if those programs didn't exist, and would've had to hope for charity, which tends to be much less reliable and less uniformly available (e.g. churches tend to help their own members first) [1]. So now that he's an upper-middle-class engineer, he doesn't have a problem paying taxes that support those kinds of things.
[1] This is actually an argument F.A. Hayek makes for why there should be a minimal state safety net, even though most of Hayek's writing is anti-socialist and pro-free-market. He argues that, otherwise, people have to rely on more cliquish safety nets (extended-family clans, churches, etc.), which produces a tribalist rather than individualist society. So, perhaps counterintuitively, a little bit of collectivism at the top level (safety net for everyone) produces more individualism throughout society (people don't feel the need to cling to these tribalist groups for safety). He supported taxation to pay for education for similar reasons, though he argued for provision of the education to be market-based (via school vouchers).
My parents have a vaguely similar view. My dad lived for a few years when he was a kid from social-security disability payments that his father received; and he went to college on a CalGrants scholarship, which at the time covered you almost fully if you had good high-school grades and were attending in-state. He would've been in quite difficult circumstances if those programs didn't exist, and would've had to hope for charity, which tends to be much less reliable and less uniformly available (e.g. churches tend to help their own members first) [1]. So now that he's an upper-middle-class engineer, he doesn't have a problem paying taxes that support those kinds of things.
[1] This is actually an argument F.A. Hayek makes for why there should be a minimal state safety net, even though most of Hayek's writing is anti-socialist and pro-free-market. He argues that, otherwise, people have to rely on more cliquish safety nets (extended-family clans, churches, etc.), which produces a tribalist rather than individualist society. So, perhaps counterintuitively, a little bit of collectivism at the top level (safety net for everyone) produces more individualism throughout society (people don't feel the need to cling to these tribalist groups for safety). He supported taxation to pay for education for similar reasons, though he argued for provision of the education to be market-based (via school vouchers).