It's easy to do two things at once when you can ask two different entities to do them for you (threads).
What's hard is thinking about how to coordinate the work they are doing for you: when to consider them done, how to ask them if they did the work successfully, what to do if they need to use the same tool at some point during the work etc.
Languages with threading require learning techniques to use them safely and many, including myself, have learned how.
Even if concurrency is easier to get right on node I'd say the node ecosystem has just layered on complexity in other ways to get to something just as difficult to use overall.
Promises and async/await sugar are only the tip of the iceberg.
It drove me crazy too, until I needed to use Puppeteer which requires you to write async/await (there are Puppeteer implementations in other languages, but they all seem to make compromises I didn't want). Generally speaking, async/await allows you to write code that looks and feels serial. Perhaps try using one of the async libraries for PHP to wrap your mind around the concept of async/await (like https://github.com/spatie/async)
Learning the event loop, then promises, then async/await is a must. Today, you probably should throw typescript on top.
A steep learning curve just to get back to a typed language that can do things concurrently.
You do get used to it, but it is a mess of stuff.