Why do student dictionaries leave out English cognates so often?

Egyptisk skip (1422-1411 f.kr.)

This is a bit of a peeve of mine and I see it in a lot of dictionaries. Take my Norwegian-English-Norwegian dictionary as an example. Let's look at the Norwegian word vare.

vare (handels-) article, product, line, commodity, -r goods

-r makes it plural (varer). Notice anything missing? We have article, product, line, commodity, goods...how about the obvious English word wares? It may seem obvious but sometimes students fail to make these connections when learning new words. German Affe and English ape is another good example of a cognate that could still be overlooked without a note in the dictionary to remind the student.

One reason given for this could be lack of space, but in the example above it should be easy enough to remove commodity and replace it with ware if that were the case.

One more example:

makt, power; (kraft) force

followed by a number of compound words...and no mention of the English cognate might.

While I'm at it I'll also mention that this dictionary of mine doesn't tell you the gender of a noun you look up on the Norwegian-English side, just the English-Norwegian side. That's helpful. So if you want to find the gender of a noun you just encountered first you:

1) look up the English meaning,
2) go to the English side and hope that you can find the word there.

It doesn't matter a great deal since I rarely use paper dictionaries anymore, but sometimes I'm left scratching my head at the design of a lot of dictionaries I own.