Apple has low memory behaviour way better optimized than Windows, so running at 8GB will not be as painful as it is with windows - but in the background the OS will constantly shuffle stuff around to avoid running out of memory, which costs performance.
16GB is the bare minimum for computer nowadays - and that applies to macs as well. I'm currently using a 16GB air m1 for some things, and I also regularly run into performance issues due to memory limits without doing heavy stuff.
With lower voltage DC you can only set the house on fire. With high voltage AC you can set the house on fire and electrocute people. In a safety oriented company you'd try to limit the parts of the device carrying 230V (or, more generally: if your device has dangerous bits, you try to keep those bits in as few places as possible, as that limits teh amount of places you need to keep safe). Now obviously this has limits - like the mentioned bed size - but I don't think we're yet at a point where this should overrule safe design principles.
I haven't seen a bambu printer myself yet - but given that the cable is undersized and not protected against side effects from bed movement I'd bet they also skimped on on making everything carrying 230V safe - in which case this is a cheaper design. I'm reasonably confident that a safe 230V heating design for a printer that size would not give you noticeably cost savings over a DC design, if at all.