Many people seem to forget that there are still countries where US laws are not in effect.

Even more interesting is the fact that even Lavabit's founder seemed to have overlooked this fact, and instead of relocating his servers and all the user data to Iceland, Norway or New Zealand, he chose to shut it down for good.

Why?

Because if he got a NSL requesting a backdoor on his servers, then it doesn't matter where the servers are located. What matters where he personally and his company are located. And you can ask Snowden how fun it is to be persona non grata.

Perhaps we had family, friends and his entire life in America, and didn't want to uproot it all to move his service overseas?

One clue is a statement Levison made is that it's not just what they asked him to do, it's also what he knows that would change our perspective of email:

“If you knew what I know about e-mail, you might not use it either.”

It simply depends on who is in your threat model.