atomarc is got it right.. it's all about saving a nickle.. or even a half a penny sometimes.
Dosen't sound like much difference, a half a cent.. but when you multiply that by a dozen or so then multiply that by the millions of vehicles they sell, it adds up.
My first experiences with wrenching on cars were the late 70's models.. and I found the newer they got the more confusing and just in general pains in the [censored] they were.. makes me appreciate working on my 60 year old trucks all the more.