> However, that carjacking in Milwaukee and Chicago specifically would follow from a nationwide omission of interlocks is not obvious as the vehicles are easily stolen without the need for personal confrontation.

I think parent-poster means that the easily-stolen cars are being used as tools of carjacking, rather than the targets of it. In particular, carjacking that occurs by somehow provoking a victim to stop on the highway shoulder, a location where attackers can't exactly arrive by foot or bus or bike. That way they don't involve a vehicle that might be observed and traced back to them.

An alternate explanation is that they meant to write something like "theft" and accidentally put down "carjacking" instead.