No.. Retailers here will not evade tax. Yes on low margin. That is the reason that prices in local retailers are higher than those online. But on local online sites, it is hardly that they can sell cheaper that what Amazon and other international sites do.
I have experience where i bought things online which is covered by international warranty, but the service center denied me the replacement / repair as i am residing locally and have purchased the item online @ international sites. Unless if i can proof that i was residing in the country that i purchased the item from, and they will accept.