Possible difference:
- Shipping charges are presented to the buyer in a visceral way before they commit to the transaction.
- Menu prices (sans tip) are presented to a diner and then they commit to the transaction. Later on, the tip rears its ugly head. This time delay is possibly enough for people to separate the tip as "later me's problem", or at least blissfully ignore it.
Also restaurants aren't all exactly the same, so lack of tipping can't be used as a strong point of comparison against their competition.
Two TVs for the same base price, one with $49.99 shipping from Best Buy, and one with free (with prime) from Amazon? I'll go with Amazon because the product is exactly the same.
Those two Italian places down the street, except one of them doesn't do tipping? Sure I'll take that into account, but more importantly, which one has better food? And which has a better base price? Which one is quicker (or maybe which is more relaxed)? Which one gets my order right? This is all just as or more important than whether or not they a part of the tipping culture.
