My guess, again, is that maybe precisely because a banner with the apostrophe would be starring us in the face, when we need to access the ESL Teachers Board 3 months later, or from an Internet cafe, we would remember the apostrophe from the banner and would try to add it to the URL...
Yes that's true about the url but what about the banner that is staring us right in the face at the top of the page? Surely that's just some image file that can be changed?
Not sure but I see very good technical reasons for the absence of apostrophe:
An apostrophe is a pain:
- can't be used in an URL
- can't be used in many software programs (for example, would generate compile errors in the most popular languages, Perl)
- can't be used in an RSS feed
- can't be used in most email addresses
- etc.