trade mark registry rule

This may be a fairly easy rule to answer for a lot of the people that frequent this forum but i guess i am just new to all this. If someone owns a brand and it is trade marked registred. can They can control who sells there items since they are the owner like for instance if you buy a item say from walmart .com and sell it on ebay for a high price and make money they can call into ebay and make them note allow you to sell there item because of copyright.

I know that its not illegal to resell brand name stuff by law so why is ebay and amazon so strict about you need permission from the brand owner to sell certian items. If that isn't the law