Why can't they all just get along?

Yahoo groups, having evolved from eGroups and, before that, OneList, dominates the world of neighborhood associations here in Austin. Periodically, one ISP or another will block mail from Ya-world, not accepting it at all, or shunting it into a junk or spam file. Why can't this be resolved? It's so stupid and wastes so much time. Most people do not understand what's happening. Many list-members also complain about something they've done themselves, which is to set their own anti-spam stuff in such a way that it's going to reject group e-mail. This week, the problem seems to be between Yahoo and Gmail, which is to say between Yahoo and Google. Just how many person-hours are spent on resolving these recurring nuisances?