Actually, the restaurants aren't all in all programs. I'm in UA and US - there are some restaurants that will grant miles for UA but not US, and visa versa. I found this out the hard way; I used my US-registered card at restaurants in the UA plan, but didn't get credit because they weren't also in the US plan.

The nice thing about UA is that the restaurants are listed on-line. I wish the other airlines would follow suit.

Also, be sure a particular restaurant is in the plan on the date you visit. In reality, the only way to be sure is to call the particular plan's 800 number. The printed directories are out of date as soon as they are printed. Another great reason to put the up-to-date listing on-line. In my case, a local restaurant seems to drop out and come back almost bi-weekly. Again, sad experience is the teacher (I lost 1000 points).

Still, with all its quirks, it's a great way to build up miles. I try to actively seek out restaurants in the plan.