>So, we punish Ann for moving by reducing her salary?
I don't see a problem with reducing Ann's pay. If rent is only $300 instead of $3000 the pay should reflect that.
If that sounds like a problem, imagine that the company pays rent or for hotel stay for visiting employees. If hotels cost $400 a night in SV and $40 a night in Argentina, should the company pay $400 a night in Argentina in order to 'equalize the pay'?