Expecting people to take an extra step to fit your needs (email) is really almost no different from asking them to share on another platform IMHO. They aren't hiding from you, in fact I'd put money on the table that they'd happily invite you into their group or you'd have access to the photos simply by being their friend on FB. You can't walk outside the bar then complain that none of your friends want to stand in the window and relay everything happening to you or get mad they might be talking about you when you can just walk right back in.

> it's no different than forcing others to smoke by the means of social pressure

Yeah... no different, except one of them causes cancer but sure, no different.