Do you have a way to resolve the issue where the surface becomes degraded and much harder to erase over time? I think it's partly due to wear and tear and partly because people try to clean off the boards with solvents that degrade the surface that is erasable. Is there a way to renew it in some way?

The ones I have usually seen do have some coated steel (presumably because they are cheaper). At home we have a glass whiteboard (tempered glass I think?), which is extremely strong and the surface very smooth.