Well, somebody DID tell Lowther. They don't use low-carbon steel in
their
magnet structures. Instead, they use an alloy that has a higher
saturation
magnetization. Seems a good fix to the problem, but it comes at a
significant
cost. These allows are far from cheap, they're hard to machine (they
tend
to be brittle and not kind to cutting tools) and they result in magnets
that
may not have the best temperature and shock stability.

It comes down, once again, to a matter of economics. Given the choice
between balance the cost of more copper vs more hard magnet material
vs more cheap steel vs more expensive exotic materials, which
combination
gives you what you need for your intended market?