Actually ... quite a few of those logos have changed over the years.
The Apple Logo used to be a rainbow
! And before that, something totally unrecognizable. (Heck, they used to be "Apple Computer" and now they are just "Apple".)
This is also why I don`t think small businesses should patent their logos ... you have to change with the times. The original rainbow apple worked great on an army-green computer. This new silvery thing looks a lot better on their white machines and white packaging materials.
I think I know what AT&Ts logo is .... I couldn`t tell you what the HP logo is.
But all 3 of those companies built brands that had nothing to do with their logo, IMO. Your identity is a sum of all your parts, not the result of something that small. (This is probably why I don`t believe in $700-2K a logo unless it can get up and sell products for you.)
I think most people can remember a word rather than a logo. Do you know what the logo is for P&G? Kleenex? Clorox? Sony? Discovery? Fisher-Price? (I have no idea either.) The logo gives you the mental picture of what it is, the same way an add with a big-screen TV that says SONY on it would make you remember SONY sells TVs. But I`m not sure that anyone actually remembers that there are 3 arrows in the NHG Consulting logo.