Well, for example, the place I work is 35 kms out in the country, and there is no public transportation out there. I suspect that they would include "reliable vehicle" as a part of their ad ... not so much to try to make sure their employees can make it to work (although that may be part of it), but if a potential employee did not have a reliable vehicle, that potential employee might want to reconsider the job, or not apply in the first place.

Also some businesses send their employees out to different sites to work or whatever. The place where I worked in Winnipeg was an Engineering office with a prototype shop in the back. When the prototypes were built, they were taken out to various locations within the city, and in the outlying areas. The engineers, and some of the engineer techs would go out to these locations to observe the prototype in action, and they used their own vehicles because the company did not have company vehicles. (They were reimbursed for their expenses of course). One of my coworkers there wanted to cycle to work in the summer on a regular basis, but he was often called out to wherever the prototypes were, and so he needed his car.

Just a couple of examples off the top of my head where the request for "reliable vehicle" is a valid one.