So I’d view it as the easy and obvious bargaining point when purchasing.
+1
as br says though, you are in effect paying for it (since if they’re willing to pay £200 for VED then they’re willing to take another £200 off the price).
But, if you hit a plateau on price, it can be easier to get them moving on other stuff, even if it has the same overall effect financially.
This happens all the time in my day job. If one party already feels they’ve given up too much, they can become entrenched. Moving on to other things that get you to where you need to be is generally an easier route than trying to bleed another part dry.
We move by millions in negotiations simply by making it more palatable for the other side to agree to.