Why do these estate owners not pass it on to their children earlier on to avoid the inheritence tax?
Because those sorts of sums changing hands would still be taxed. My uncle won a few million on the lottery and it was quite difficult to give any large sums of it away without incurring big tax losses. Also you don’t generally pass on your estate to your children (plural) just to one. Estates need to be huge otherwise they don’t work, if you split them with each generation you end up with several large, loss making encumbrances rather than one functioning, income generating estate.
If you pass it all on to one then its difficult to decide which of your feckless idiot offspring will make the least worst hash of it all, and if you make the wrong decision you’ve got to watch them arse it all up from the sidelines as well as deal with any family fall out that results. Better to have all that happen after you’re dead.
It would be a different deal if we had the Japanese tradition of adopting adults where you recruit the best candidate to inherit your estate then legally adopt them.
In this case its a no-loose situation to sell the mountain (instead of selling a few tenanted properties), those properties are the goose that lays the golden eggs, if you sell them your estate income falls but your outgoings don’t. Nobody pays rent to use the mountain and as the estate owner you don’t loose the view of the mountain or access to, but you do shed any responsibility to maintain a highly trafficked bit of countryside. But that traffic is still attracting B&B nights and coffee and cake sales in properties that you still get rent from.