> OK, but why just the land? Trusts hold stock, too

The stock is taxed indirectly. Georgism holds that all wealth fundamentally comes from the land. This isn't completely true in the digital age but it is still true enough.

> Their heirs receive the dividends from that stock

If you tax income it never goes away. You just take a portion of whatever is there. If you tax wealth then the wealth is eventually drawn completely into the society. That's the fundamental difference. LVT is a tax on wealth.