[LeifCarrotson]

Because all the letters already look weird. The fact that the style of B and D are very different doesn't matter because the reader doesn't know what the other letter ought to look like.

Yes, if you compared them side by side with an official and the fake it would be easy to see. But when just reading, all the letters already look weird.

[occamrazor]

But Germans do know very well how they _should_ look like, because they see those characters thousands times every day.