I agree with you 101%. I have been a Graphic Artist for 54 years, including 48 since I graduated with my BS in Communications and Graphic Design, and 6 years saving money for college by doing paste-up (back when we actually had to stick things down on a bigger sheet).
I am the second generation of Graphics person in my family, my daughter who is also degreed in the field is the 3rd generation, and my granddaughter on one side, and a grandson from my other daughter looks like we'll be going for four gens. but I digress - - - - - -
Computers and "graphic programs" are largely to blame. "Oh, I can slap it together with a free Shutterfly and just pay $6.19 for S/H. Fine, go ahead! I've used it, too, but I've used it with the grounding of a half-century (Gosh, that makes me feel SO old) of practice!
My daughter has the same problem. She normally bills out at $50-60/hr., with a 2 hr minimum on anything bigger than a flyer, plus she has an Etsy shop "Doorpost Truth". Then she gets requests from the church where "everyone is a volunteer", and where a "simple little thing" turns into a nightmare of falling dominoes. SHe'd like to help out, but, where do you draw the line??
Ironically, these programs that let people think they are all "graphic artists" don't even know the difference between a "type face" and a "font", since they are NOT interchangeable. sigh
So, stand your ground. And if they want you to store their files, charge them as "file maintenance fee" as well. Good luck.