I am guessing that cost is less of an issue than meeting code and keeping the customer happy.
We've address the code issue: yes, the switches can be located behind the fridge. What remains is having fun giving the OP ways to give the customer what they are asking for without going crazy (that is the electrician not going crazy), possibly improving the design so that the customer gets what they asked for _and_ what they can actually use.
These switches will be on a wall, presumably next to a doorway and partially behind a fridge.
We've already mentioned putting all 3 switches into a single gang so that they are all as close to the open side as possible.
Wireless has been brought up.
Perhaps rotating the gang box 90 degrees and putting the switches vertically in a row. (Use
https://www.lowes.com/pd/Eaton-Sing...-with-LED-Combination-Light-Switch/1001438288 to make the switches operate vertically and be closer to the edge.)
But the most fun would be some sort of mechanical linkage switchplate, so that you have 3 normal switches, but levers that make them easy to reach on the open side behind the fridge. Like
https://linnelldesign.com/collectio...s/double-rack-gear-light-switch-cover-plate-1 in concept but implemented totally differently
-Jon