Lightening cables are not a standard and thus Apple dictates terms even with non-Apple lightening cables. As lightening cables are not an industry standard the prices are influenced by Apple and artificially inflated (even for non-Apple ones). And they can only be used with Apple devices. (Lightening cables have seen a recent price fall only after Apple shifted to USB-C for some iDevices, as the market fears Apple is already preparing to switch to USB-C).
USB-C cables will be even cheaper in the future as they are standardised, and since they can be used with multiple devices (due to such regulations) you need to buy fewer of them too.
What I can say, is that in France on Amazon, USB-C cables and Lightning cables had similar prices when I last bought mine a few years ago. I usually compare Amazon Basics and Ugreen / Aukey brands.
I’ve seen this argument a few times “yay now I only have to take one cable on holiday”. Sure, unless you want to charge two devices at once while you’re sleeping, perhaps… it’s an unrelated argument to which connector is better.
Apart from the cable that came in my iPhone 7's box many years ago (which still works perfectly and, excluding a little dirt, looks like new), all my other lightning cables are off-brand ones that cost much less than $20 apiece. More like 10.
Some of them (Aukey brand) developed a wonky connection after a while, or only work on one side. The others (Amazon Basics) still work perfectly, after spending uncountable hours in the sun and rain powering my phone on my motorbike's handlebars.
All this without any kind of law (I'm in the EU).