Some of the taxes have a variety of inputs, others just produce a flat rate. Inheritance tax is the latter. For comparison, luxury goods tax is linked to wealthy membership. It would make sense if this were in the same category, as for example, it wouldn’t produce much for the government if at some time in the next 50 years they got a slice of the condo-apartment I own, but when the wealthy die, the government would get a notable amount of money from taxing their estates.
I don’t think any one actually dies in game, except for the abortion low, and by lowering the lifespan value.