[Marcello]

ERA has several issues.
The early models, such as Blazer or Kontakt EDZ generated shrapnel when they detonated, which could be an additional danger to nearby infantry.
Then once a tile had detonated the area was left unprotected; this could be an issue especially for those arrays relying on relatively large blocks such as Blazer or Kontakt-5.
So while ERA has its own advantages it also has drawbacks which have limited its deployment in the West.
That being said it has seen some use in the western block too, most Bradley in Iraq are mounting ERA tiles for protection against RPGs, for example.