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.
Yes, it probably will work like how it does today, but instead of a bank account where people keep their money and subject to arbitrary power, they can keep it on the bitcoin blockchain. Than they just top up a prepaid-card/lighting network channel for everyday small purchases, just like you can withdraw cash from an ATM.
It isn't that complicated, also, with additional layered solutions pegging back to the bitcoin network, different transfer needs (like streaming money with micro/nano transactions) will have different layers, with varying amount of centralized services, depending on the need for trust.
The point of the bitcoin network would be the absolute uncensorable arbiter of truth, which all these layers/sidechains/network can rely on - the gold standard, so to speak.
That is why decentralization, censorship resistance, open access are the true value of bitcoin, not cheap transactions. Those can be solved on the layering technologies - without a robust, unyielding base, we will have neither of them.