Yep companies love capitalism and open market until they start loosing to competitors. Then suddenly government intervention and protection seems like a wonderful idea.

Because it takes 2-3 decades to build up the battery industry and supply chain.

Copying BYD is what Tesla is doing to some extent (BYD also copied aspects of Tesla). They are trying to design their own batteries, build their own plants and so on. But Tesla started going in that direction around 2017 and they were still a pretty small company then. Its crazy that Tesla dared go in that direction at all.

BYD came from the other direction, it was started as a battery manufacturing company. And specifically LFP type batteries, ironically a technology pioneered in the West. Tesla already has NMC batteries, that was their first major bet. But turns out, for the great mass of cars, LFP batteries are what you want, and China was already dominating in LFP. In China lower range cars had more of a market, so China adopted LFP aggressively while the West was still focusing on longer range models. Tesla is currently setting up its own manufacturing plant for LFP.

But BYD is part of China larger strategy for their automotive export industry. They realized that alternative fuel vehicles (they weren't sure what exactly) would eventually replace current technology and they hopped, the current industry. Battery electric turned out to be the clear winner in this and they pushed the industry forward, everything from the mines to all the complex refining steps. Lots of long term investments from China's investment banks, lead by the state but with lots of private investment as well. Initially they gave automakers from China subsidies and then eventually the reduced subsidies making it clear that they wanted a competitive industry, and the car makers had to sink or swim. Out of that China now has the two of the largest battery producers on the planet, CATL and BYD, completely dominating the battery market. This is not something you just copy, this is 20-30 years of work.

Now, why did other companies like Toyota or VW or GM not do this. Now Toyota and Japan in general was completely obsessed with hydrogen and didn't really believe in battery electric, and arguably still don't. VW and GM were large assembly companies, they looked at batteries like steel, or seats or something. They outsourced all that stuff and by the time they actually realized battery electric was the future, about 15 years after China, it was clear that these companies were simply not set up to do vertical integration, it was literally the opposite thing they had been doing for 30 years. They also had massive software issues that they also need to figure out at the same time. And when they tried they mostly just invested in battery cell assembly plants with partners, they had the finances but instead of spending 15 years investing in battery supply chain, they gave it to shareholders or invested in the wrong things.

Now the other maybe more interesting question is, why did other battery companies not do the same as BYD. Panasonic is from Japan and despite building the first true automotive size factory with Tesla, they only believed in the technology to a limited extend and didn't go after that market as aggressively as they should have, and thus have lost market share every year. LG came to batteries from the electronics side and they focused on being a major supplier, who in their estimation made more money, and also Korea car industry was already dominated by Hyundai so they would compete with their own countries champion.

This really is just an example of China long term strategy paying off. The focused on 'New Energy' Vehicles, and instead of focusing on one thing like Japan, they reinforced success continuously when batteries turned out the best. Of course they were also lucky, their market happened to be much more open to smaller lower range cars, making LFP batteries an option, while US LFP companies failed to get investment. In the West, emission regulations mostly targeted improving efficiency of ICE engines and no long term supply chain investment at all was done, especially for mining.

So simply 'copying' that isn't that easy. As somebody that has watched this for a long time. It mostly just seems like western companies and western politics is consistently 10-20 years behind the curve. Tesla is the only company that was really on the ball, but it takes 10+ years to scale the old legacy car building no matter if your ideas are correct, but the danger Tesla also pushed China into being even more aggressive competing with Tesla.

They claim to have delivered L4 autonomous parking, not full L4.