I think Ed is getting very well paid for taking the brunt of the criticism, but I can imagine he is under strict instructions from the Board/owners to not pay over a certain amount for a player unless he can produce an excellent case for the financial investment. So for instance if he could pay £150m for Neymar, it probably would be approved because of the increased commercial revenues . But Sancho is a good footballing transfer, not someone who will seriously move the commercial income column, at least not for some years yet. This is far harder to sell to non-footballing owners. Pogba apparently ticked both boxes as far as the owners were concerned so a big expenditure was readily agreed. In the covid year, this just gets harder to convince to pay over a limit, which I guess is 100mEuro.
At the same time Dortmund's business model relies on them being hard negotiators as they need everyone to realise they have excellent talent but it comes at a top price. They cannot afford to be seen to back down.
My guess for what its worth is that Ed will find it just as difficult next year, paradoxically the only way he will be able to persuade the owners to pay more is if other clubs are prepared to slug it out for the transfer, this 'proves' value to the owners. As it is this year United are the only ones prepared to pay 100mEuro so the owners have no indication from the market that the guy is worth this nevermind more.
Sancho is good, but its a pretty poor indicator of market talent if he is the only RW worth buying, maybe GN is right, United are really just awful at this.