One of the problems with LN is that, in order to actually receive BTC (on the Bitcoin blockchain) that you can sell, you almost certainly need to go through multiple LN nodes. Due to this, the node in this path with the
smallest capacity will determine the maximum amount you can transfer (before needing to touch the blockchain). From the stats we can see that "
Average Channel Capacity" is 0.025 BTC/$91.77, and that 50% of channels have a capacity of 0.005 BTC/$18.35, which means the minimum, for any given path, is likely close to $20.
So, in other words, you can expect to transfer, roughly, $20 until you need to touch the blockchain again (in order to fund a channel), which means that sending ~$20 over LN is as expensive as doing it in a normal Bitcoin transaction.
LN doesn't scale because of this. People keep pretending that adding new nodes is a sign of success, when in fact adding new nodes to LN decreases performance -- because the smallest-capacity channel on a path determines how much can be sent through that path until you have to touch the blockchain. If two or more channels in a path need to be refilled, you've spent more on a LN transfer than you would have on a regular Bitcoin transaction (on-blockchain).