They usually (or often) have them, but often the most common tunes in the first few Real Book volumes (and other standards) have been memorized so they never actually pull them out. When I used to sit in with some guys from the local university, they'd usually play everything from memory and only pull out the fakebook for newbies/guys like me who didn't know the songs they were playing [so we could 'fake' our way through].

A lot of those guys would pride themselves on having played along with the recordings dozens or hundreds of times (and often with computer transposition) so they could play the tunes with their eyes shut, in any key and at any tempo.