The property tax idea is an interesting and insightful thought exercise, but it misses one key point: To own isn't just the right to exclude; it's also the right to dispose of. This tax idea only addresses point A while ignoring point B.
I was explicitly trying not to be ruled by our preconceived notions of what it means to own. Given that ownership of software isn't quite how we used to do it, are there benefits to changing the rules around a little bit elsewhere as well? Basically, our planet is getting crowded enough that giving people so many rights bundled up in 'ownership' is starting to crack at the seams. In my opinion :)
I think a price tax would be incredibly useful in the domain of software, and IP generally. A home is different from any other investment in that we live in our homes, so they're so much more than just a credit and debit sheet. However, a tax on derelict IP would be amazing. Patent trolls would be doomed, and rightfully so. Perhaps the tax could be deferred for a period of time for businesses that are actively developing a revenue stream off their idea, because I could see it being burdensome for a startup with limited resources. However, it could do wonders for innovation.