The exposure to silica comes from cutting and grinding - and there is probably more exposure to cutting and grinding from natural stone (first at the quarry and second in production).

I think the important distinction is that with natural stone, much more is cut to fit from the factory (which is easier to handle dust) vs cut on site.

Yeah, I'm pretty sure that nobody tries to cut granite on site with an angle grinder. It's so difficult because the material is so hard.

Granite countertops are typically cut off-site with a waterjet, which creates zero dust.

I wonder why those parts are not made in the desired shape already with no need to cut or sand in place.

I assume it's because kitchens and bathrooms aren't made in standardized sizes to fit standardized counters.

No perfect walls (also changes w/ temperature/humidity), drilling holes, misalignment, imperfect measurements...

Since it's a luxury but not a super expensive product, the more expensive process of precise measurement, off-site waterjet/laser cutting is not suitable.

This I suspect nails the question of "why doesn't natural silica-containing stone cause the same problems?" asked several times elsethread.

It's been said elsewhere here, but the ban isn't because of manufacturing. The stuff can and generally is handled very safely during manufacturing, and they appear confident they can sue / jail the odd cowboy shop that doesn't comply.

What they aren't confident is their ability to force the installers handle it safely. When it gets to the site there is often a corner to be shaved, or a unexpected hole needed. It only takes slightly more effort to use a wet saw, but to contractors time is money and it's their health they are putting as risk - so it's OK, right? The site is typically a new house or small business. Policing those sites effectively is prohibitively costly, suing for the consequences after they happen doesn't work because the disease takes years to manifest so they've killed a few people by the time it happens.

So in typical Australian fashion they've decided people making decisions in their 20's they maim or kill them in their 30's is not OK (that is what's happening), so they take what seems drastic action. It's entirely in keeping with the Australian way. We were the first insist on plain paper packaging for cigarettes for example, ditto on seat belts, we enforce total alcohol bans in towns where alcohol related violence is deemed too high (typically we see a 60% drop in alcohol related crime when that happens).