This is not quite correct, it an insurance company requirement, not the AB registry, and if you have an out of province insurance underwriter they may never request an inspection.
I buy and swap junkers/heaps of all sorts and have never been required to produce a mechanical inspection for registration. And since my insurance is an Ontario based provider they have never requested a mechanical.
Same with my motorcycles, it is an Alberta based provider and they simply ask the same boilerplate, VIN, usage, desired coverage.
Personally it's a breath of fresh air, the "safety inspection" dance has become a cottage industry back in Nova Scotia, nickle and dime charges to certify otherwise serviceable vehicles.