Eventually I found the ultimate source: the tax code.
IRC.§ 1.280F-6 (c) (3) clearly indicates that "for compensation or hire" means to what can be included in passenger automobiles, in § 1.280F-6 (b) (1) (ii) still defines "any other property used as a means of transportation" as Listed Property.
So, the 4562 instructions just mean to say "passenger automobiles" exclude taxi or Uber (purely used for Uber).
