What I'm wondering is: why are Americans advised to "wash with like colors" while Britons are instructed to "wash with similar colours"? Would there be any danger of anyone fluent in either dialect misunderstanding the other? Is "similar" in this context a conspicuously un-American usage, or "like" a shocking mangling of the Queen's English?
In America, vocabulary dimishes you!
Our educational system sucks and smart people are looked down upon. Therefore, we 1984 our language so we don't sound like nerdy liberal show-offs.
While I like the explanations above, I think that here in the US "like colors" just happens to be the phrase that's always used on clothes. The Swedish manufacturer is probably just working from some kind of textile industry glossary. Although it seems silly for this phrase, there may be other laundry expressions which differ more radically in the US and UK. Laundromat vs. Laundrette? Jumper vs. Sweater?
It's a typo. They left out some commas, it should read "WASH WITH, LIKE, COLORS"
Don't be too hard on them, they're just trying to follow local customs.