I think they are generally for quick snap shooting, and not really for precision, and it's pretty common to see better during low light without looking through the glass. No doubt, there is light transmission inefficiency. I think some scopes have quite a bit more brightness options than yours, so some probably go quite a bit lower, but generally the problem is they aren't bright enough in bright conditions.
See if you can look through a really good scope, side by side with yours. It can be impressive, but pricey. A first focal plane scope, where the reticle shrinks and grows with magnification changes, can be a different ball game. On low power, some might see a fancy reticle as useless, because it's so small, but lit or not one can often use it like a dot, and pick things up really quickly with both eyes open.
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