Why would lightning layer not be for the average Joe? It could be literally without fees if he and Starbucks agree there should be no fees. What would be the incentive for any of sides, he and Starbucks, not to do it?
It is certainly possible and might even happen for a while but you don't need the worlds most secure network to secure coffee funds. Opening a lightning channel could still cost Starbucks or the customer $10-$100 in fees to open or close on the bitcoin network. More likely Starbucks would open a channel with your bank and it's suppliers and close the channel each day, week, month to settle the account.
I disagree. As far as i understood the Lightning protocol, although it's not easy and maybe I'm mistaken, if millions of customers open long lasting channel with Sturbucks there is no need to close all of them to bring funds back to fiat. Lighning channels can transfer the funds between each another, and in the end of the day Starbacks can transfer the funds from all daily transactions to "closing" channel (to call it that way) and confirm all of them from arbitrarily large number of customers with paying one single transaction fee for closing the "closing" channel. I believe they would gladly pay one opening/closing fee for each day, regarding the potential number of transactions.
I don't think opening a channel with Starbucks and every other company you deal with is going to be the most efficient use of LN. If the average Joe does use LN, he will open channels with a bank or service provider like Coinbase. That provider will have open channels with major companies like Starbucks and your employer so that there are payments being made in both directions. The companies are paying out to some people and being paid in by others but only the net difference is recorded to the blockchain periodically. However, most people will just leave their coins with the bank/provider to handle the details so I still don't think the average Joe will use LN. The average person reading this thread might though.