The x% does not value with the use of the land. An apartment block owner would self assess their land as much more valuable, and then also pay back x% of that much higher land assessment in taxes each year, yes. And if someone came by and decided that e.g. that $5 million apartment land unit would be better as a $5 million parking lot, they could certainly pay them $5 million to do so.
But they may later find out that the parking lot isn't really worth $5 million, because it's harder to make the money to justify the x% of $5 million tax you're paying on it with a parking lot than with an apartment complex. They may then drop their valuation to $3 million, or $2 million, to reduce the total amount they pay in tax each year. But then of course they may run a greater risk of being forced to sell themselves -- perhaps even back to the original apartment runner they paid $5 million to before.
But they may later find out that the parking lot isn't really worth $5 million, because it's harder to make the money to justify the x% of $5 million tax you're paying on it with a parking lot than with an apartment complex. They may then drop their valuation to $3 million, or $2 million, to reduce the total amount they pay in tax each year. But then of course they may run a greater risk of being forced to sell themselves -- perhaps even back to the original apartment runner they paid $5 million to before.