I've been told in the past that the key factor in Toyota success is their relationship with their suppliers. A top notch supply chain with just in time processes bundled with reasonable proxy stocks?
Would love to read about their automation level compared to US or EU companies
It's kind of a cliche at this point - but a good start is 'The Toyota Way', which talks about developing people. I'd also be interested if you can find an authoritative source. I just have a lot of news articles - a good overview is this one in industryweek (https://www.industryweek.com/operations/tesla-vs-tps-seeking...).
The basic principle is somewhat obvious - automation is efficient, but inflexible. That often leads to machines sitting idle, or the overproduction of unsaleable stock. So it's a kind of poison chalice - it looks like you'll reap huge profits, but if your car doesn't sell well, you're screwed. If you invest in people instead, you can react to changing economic conditions.
https://www.thedrive.com/tech/26955/inside-toyotas-takaoka-2...