Perhaps you should show them a hand pump. Tell them it's like filling a bicycle tire.
Honestly, though, I think a lot of prospective customers would benefit from being presented something that can be filled with a hand pump at first. A 2 or 3K PSI tube reservoir with a volume of 250cc isn't a terrible chore to fill manually. The cost of the pump at $100 or less makes the whole thing a little easier to swallow.
I realize also that in order to get a shooter to spend money on an airgun, the tendency is to go for big power so they don't feel like they're giving up much by diverting funds from their powder burning budgets. That usually goes hand in hand with large bottle fed airguns that almost beg to be filled with a relatively expensive compressor. I should think, however, out in farm and ranch country the case could be made for less powerful and noisy airguns for eliminating smaller pests and game. These could keep costs down, allowing someone to dip their toe in the water. From there, they might blossom into a full on raging lunatic airgunner like the rest of us around here.
But they have to start somewhere and that might be a smaller is better approach. Just my $0.02...