Not really. We live in a digital age where our ability to contact anyone is no more than a few key strokes away. All it took me was about 20-30 minutes to writeup an email which included our band name, our price, our contact info, and links to our promo pages. This one email can be used time and time again for any venue we're interested in contacting. The only thing I need to change when contacting someone new is the heading and name of the person I'm writing to.
Likewise with thank you emails, all I have to do is change the name of the venue and the person I'm writing towards. I always include a link with our gig schedule attached to it, and I ask them to refer to it if they'd like to book us again in the future. The amount of effort it takes is so ridiculously small compared to what our advertising guy does (creating flyers, printing them, hanging them up, etc...) that if he were to ask for a larger cut of gig money I'd be more inclined to give him it than take one for myself.
In addition, once your band is somewhat established in a city, venues will start contacting you before you ever even try to contact them. At that point the only real difficulty comes with establishing whether or not every band member is open for any given date. But even still, the leg work is basically nonexistent except for contacting out of town venues, and even then I still have that catch-all, master email that works just fine even for those gigs.
I can't speak for every band out there, but if certain members aren't interested in booking gigs then it probably has more to do with them either being shy in nature or just incredibly lazy. It's really not that hard of a thing to do, and it's really not that time consuming - at least in this digital age.