My simplest laptop in current use has 4 times more memory than my current phone and I probably would need to make huge compromises to live with half as much. A lot of the chips in phones don't even have external memory buses. A top-of-the-line iPad Pro sports an 8-core asymmetrical core design, with 4 fast cores and 4 slow ones and, overall, is slower than a 2-core Core M-based MacBook (although it feels great because iOS does a lot less than macOS).

Also, Apple doesn't make its own A-series processors - it uses TSMC for that.