I'm an Australian (block style symbol :) working on a US campus of a multinational company, and we use the wiggly heater style symbol in all schematics generated domestically.
Some European companies that we acquired still use the box symbol several years after acquisition. They don't want the effort of updating their CAD libraries, since every single schematic would be affected.
Just don't mix and match on the same schematic, and anybody who complains can safely be ignored. It would only be an issue if you used both styles in one dwg, since there is a semantic difference between the two symbols.