Because you can tax the minority (higher income) and because people see the benefits of taxation. If taxes were per-head we'd probably see people voting them as

Because you can tax the minority (higher income) and because people see the benefits of taxation. If taxes were per-head we'd probably see people voting them as low as possible. You can also tax things indirectly or in a more abstract way like a VAT or corporate taxes. Voters keeping taxes too low is a problem for us too though.