Most any photo of a street scene from the era of AD trucks and before show cars parked head-in, not parallel. I think that shoots the theory of "safety on the curb side". But I have no better theory.

"It's just a phase. He'll grow out of it." Mama, 1964

1956 Chevy 1/2-ton 3100
1953 Chevy 6100 "The Yard dog"
1954 GMC Suburban Now with a new proud owner.