Lightning was not ready when Bitcoin capacity was crippled by the aforementioned tiny cabal of developers in favor of Lightning.
Lightning remains unready, forever 18 months away from the promised usable technology.
There's a myriad of reasons people don't buy things with third-party checks.
This is provably false. Lightning is huge and growing:
* more than $6 billion USD in liquidity
* nearly 11,000 nodes
* tens of thousands of transactions daily
* a growing ecosystem (https://www.lopp.net/lightning-information.html)
You can see the real-time stats at https://1ml.com/
There is only $6 million in capacity, not $6 billion.
Daily transactions are more likely in the few hundreds per day, not tens of thousands. Although this can't be determined with accuracy.