I think @Nextgrid hit the nail on the head. If you're being brought in to use a customer specified stack/platform, you're just contract labor. That makes you a

I think @Nextgrid hit the nail on the head. If you're being brought in to use a customer specified stack/platform, you're just contract labor. That makes you a commodity, and you're likely to draw commodity compensation for same. Your goal should be to position your self as somebody who is qualified - no, uniquely qualified - to solve a problem for the customer. Get yourself in that position, and you'll be the one dictating the technical details of the solution, and you'll be able to charge more.