Very true. I've had people look at my ~50% open rates and think they were low.. but they were sending product updates to a dedicated list of people who wanted to learn about that product. And it's easy to look down on e-commerce folks getting 10-20% but.. they're sending mails every day and making 6 figures a mailing, etc.

It's so contextual it's ridiculous. Stats from companies like MailChimp try to break things down by 'industry' but it's still not all that useful to compare against. The type of mail is just as important (industry news, personal announcements, product promos, sales, etc.)