I know that the legislation is very varied around the world, but as far as I know in most countries, it is regulated as a financial asset and not as a currency, therefore, every time you spend you create a taxable event.
Legislation might explicitly exclude assets held for daily use from taxation as in some countries. Still, the tax authority might have a different opinion than the Bitcoin user.
I believe that in countries where bitcoin is regulated as a financial asset, it will be difficult to use it for day-to-day payments, even with LN. I can't imagine people filing their tax returns with thousands and thousands of payments. Unless an app is created that does it automatically, but that would mean giving the data of all your transactions to a third-party.
Yes, as long as there is the possibility of creating taxable events, it might be useful to have a way to export transaction data from the wallet software in order to avoid the taxable gains from being estimated.