Simple answer is because if you don’t associate a monetary value, nobody values it – or you!
Discount is not a very nice word either but if you have to discount to meet a client’s budget then it is important to also reduce the service or product offering that you are delivering.
Nobody expects to buy a Rolls Royce for the same price as a Ford Focus and that is because these are completely value brands.
Each can justify their cost in their own way and it is perfectly reasonable that we, as designers, should do the same. If the client wants that extra slider or graphic element but cannot afford to pay for it, then they should not get it.
There is probably a compromise between the two prices that is a true value proposition for you both.