This is only rational if a seller has a very high level of certainty about who will be a buyer. I purchased my first road bike (and it's not a cheapie) with very little knowledge about cycling other than that I was very I wanted to do it. I didn't own pedals or shoes at the time, I purchased them with the bike. My girlfriend recently bought herself an ~$2K bike from a similar position of not owning pedals and shoes. Assessing whether someone intends to buy a bike primarily on whether they brought pedals and shoes with them to a store would be a very, very stupid means of assessment. Electing to not spend a few minutes setting up a bike all but guarantees that a sale will not be made.