A Jeep, sport utility vehicle (SUV), or truck type with at least 15-inch tire rims and at least eight inches of clearance from the lowest point of the frame, body, suspension, or differential to the ground. Four wheel drive vehicles have a driveshaft that can directly power each wheel at the same time and a transfer case that can shift between powering two wheel or four wheels in low or high gear. All wheel drive (AWD) vehicles do not meet this definition.
First, note that all recent Crosstrek models have 17" wheels and minimum ground clearance of 8.7" or more, so the only potential issue is "all wheel drive".
The last sentence is at best non-normative, so the actual requirements appear to be:
1. The ability to power all four wheels at once.
2. A drivetrain that includes a transfer case capable of switching between two- and four-wheel drive and, in four-wheel-drive mode, between two distinct gear ratios.
In particular, the regulation says nothing about differential locks.
Obviously the Crosstrek has (1), but not (2), so the citation is valid.
OTOH, (2) not only excludes Subaru-style all-wheel-drive systems and AFAIK all electric vehicles, but also several full-time four-wheel drive vehicles clearly designed for off-road use, including the Toyota Land Cruiser[2] and the military-issue AM General HMMVW[3], for no other reason than the lack of a two-wheel drive mode.
[1] https://www.nps.gov/cany/learn/management/compendium.htm
[2] https://www.landcruiserforum.com/manuals/2024-toyota-landcru...
[3] https://gear-report.com/wp-content/uploads/2017/03/Operators...