1) No one drives 60 mph on any of the highways I regularly use...maybe you live in Slowville, but 70-75 mph is the new norm where I live, with many people pressing beyond that. So yes, everyone can milk out those extra mpg's by going 60 mph, but on a lot of highway stretches, 60 mph just isn't realistic (unless you don't mind getting passed by everyone else going 10-15mph faster).
2) Your hand calculations may be fairly close to the EPA ratings, but for the average F-150 owner that isn't the case. The average mpg on fuelly for the 4x4 3.5l F-150 is ~16.5 mpg (compared to the EPA rating of 19 mpg). There are plenty of magazine articles covering this discrepancy between the EPA ratings and the F-150's real world mpg results. Likewise, there are similar accounts that are starting to emerge in regards to the new Ranger ecoboost:
Car & Driver
Pickup Trucks
So if you want to stick your head in the sand and pretend that Ford has some magical solution to the mpg issue with their ecoboost family, fine go ahead. The reality is that their engines are only slightly more efficient, or in some instances slightly less efficient, compared to all the other gasoline trucks on the market. This issue is well documented, and while the results on fuelly and magazine articles aren't 100% perfect, they're certainly a lot more credible than the echo-chamber induced hype that exists on facebook pages and brand-specific forums.
3) The EPA spot-checks, but at the end of the day it's a government agency that is imperfect and prone to mistakes just like everything else. Theoretically, the EPA testing standards were supposed to prevent OEM's from producing too much pollution, but we've already seen one OEM totally bypass those testing procedures...the only reason VW got caught was because of the research being conducted by a non-government organization.
So yeah, the EPA says that several gasoline 1/2 tons are rated at 18-19mpg combined; the reality is that most 1/2 tons (in the aggregate) aren't getting those kinds of results. When you apply an honest perspective to the something like the Tundra, it becomes apparent that 14 mpg, while it's lower, isn't all that abnormal compared to the rest of the segment.
Edit: And highway mileage should be calculated going from pump to pump...if all you're doing is grabbing the instantaneous average off the vehicle's dash, you're simply kidding yourself.