You can almost always find gift cards for these services that are 10-20% off. And once you stop using these services for a short while, they bombard you with 20-40% discounts to pull you back.
So it's likely the fees are too high because they need to offset the marketing spend, but then the reason why people avoid or use these services not very frequently is because of the high fees.
Maybe there is a world in which spending less on marketing and lowering the fees could result in lower acquisition cost and higher retention.