Don't know about Facebook specifically, but WM-SE did get sued recently for publishing photographs of public art on a non-commercial website:
Also, suing people who have no idea about copyright and use random images on their low-traffic and/or personal blogs/websites is a popular niche market;
the web is full of stories like that. If the right for licensing building photos stays with the copyright owner, Cavada has no way of guaranteeing some will not start doing it (or sell the rights to do it) as a side income. The alternative is to create a collection society which is the sole organization permitted to pursue copyright violations (that's how fees are collected for e.g. playing music in your store in many countries); in which case the upkeep costs of that society have to be collected at the very least, so again they will have to sue someone or otherwise make them pay.