I grew up in Britain where the standard oil change interval for all vehicles I've ever come across is 12000 miles or 12 months. I was surprised to see oil changes at 3000 miles when I moved to the USA. Either American engine oil is complete junk and doesn't last, or we're being scammed.
Actually very few vehicles made (US spec) in the last 15 years have a 3K mile interval. The 3mo/3K mile interval is a byproduct of advertising and the strong emergence of Japanese imports in the late 70s and early 80s. Most of those cars had their intervals converted from KMs to miles, so the intervals were weird (3417mi, 3728mi, etc.) Most people just ran with it and never questioned it. Especially after being bombarded with it for years and the support it found in the repair industry.
The 98 Blazer I had was 7K for standard service and 5K for severe on dino. I usually did 8K to 9k with Mobil 1 syn, but later went to yearly changes at about 12K with Mobil 1 EP. Had one change where I went 18K on accident, oil still tested good. I was very hard on this vehicle (including emergency services use in a cold climate) and the engine served me without problems from 32K till I sold it last summer with ~170K. The new owner has had no issues other than a faulty fuel injector.
My 91 Volvo (turbo) was 5K on dino. Our company's mid-90s fleet vehicles (E250 and E350 vans) have a severe service recommendation of 4K. The newer 06+ models are 7500 miles on dino for severe service. Until Honda put the Maintenance Minders in their cars, the 03-06 Accord had 10K (4cyl) and 7.5K (V6) intervals on dino oil. BMW has been 10K on synthetic with Mercedes and VW for at least 10 to 15 years. Chevy says up to 15K on their C6 Vettes (including the Z06), depending on the life monitor. My friends 08 averages about 9K and he is hard as hell on the car (+ mods = 550HP to the rear.)
A few years back a group took a bunch of Disco IIs on a trek through the US, Central & South America, Australia, Asia and Russia. 41K miles, no oil change. Believe they ran Mobil 1 EP.
Other option if you still feel uncomfortable, just have someone do it for you. Provide the oil and filter. The $21 it would cost (average) is worth not worrying about the hassle or any legal issues.