First of all for now, 30 cents worth of BTC was enough for me to get confirmation approximately in 10 minutes. Also, such things as LN are designed to simplify such "coffee transactions". And this solution becomes pretty popular.
The other question is that why should you pay those $2-3 in BTC while there is a chance that tomorrow it could become a $4 worth of BTC? At this point it seems much easier to pay in cash.
Thats the mindset of investors lol. many users prefer to use bitcoin for investment rather than for currency, they can get a greater value the next day than to spend their bitcoin. I think that's a different problem.
Let's focus at side the user of bitcoin as a currency not an investor. Of course LN is very useful for all of us for the speed of transactions. of course I will use bitcoin if fee and speed confirmation are good enough for me