Property itself is not a voluntary contract between two parties. If you asked a poor person whether they "volunteer" to let a rich person live in a mansion while they live in a trailer, they'd obviously say no. It's only by a threat of violence that the rich person gets to keep that mansion.

Which is not to say that there aren't strong arguments to be made for a system based on property rights, but the idea that they're more "voluntary" than taxation is ridiculous.