That's not true, the safety expenses should be mandated and everyone's prices will increase accordingly. Prices are set according to costs and in the developed world, safety is a required cost. It could happen overnight if the big customers actually required it. Imagine if Walmart suspended billions of dollars worth of contracts until safety standards were met.
Right now, Bangladesh needs wealth more than anything else. Once they have wealth, they can spend it on things like OSHA.
Western nations could incentivize this by not assessing fines for firms caught producing their products in unsafe factories (I assume a couple billion dollar fine would be more impactful to Apple than a scathing NY Times article).
Because they would have nowhere to move to.
First... China has a humongous work force, which solely on numbers no other country can compete with, you need whole continents to get the same mass of workforce.
Second, in comparison to the rest of the BRIC competitors - Chinese workforce is relatively homogenous, well educated and most importantly of all they have a work ethic (Brazil? Hahahahah).
Third, low price is not the sole reason why stuff is produced in China (Go read why Ipad production is never returning to the US according to Steve Jobs).
This is a weird way to frame things, as though workers don't really mind being killed or injured on the job. Safety is management's responsibility, not an employee choice.
There are many things we could do to reduce your first world risk of death - mandate that all cars are have a mechanically enforced speed limit of 20mph, for example. We choose not to. Why?
When there is a gun pointed at your head, you do not have a real choice.
It's a matter of probabilities, not certainty. And workers quite often DO prefer to trade off safety against other concerns. Not just pay, either. Convenience is a big one. When I worked at a factory in China, I was told the people using heavy machinery had safety goggles available but often preferred not to wear their googles, because doing so was hot and uncomfortable. Management would nag people to do so but wouldn't require it. In that sort of circumstance, giving workers objectively more freedom and personal responsibility allows them to be less safe - but more comfortable! - compared to how they would be in the US with OSHA breathing down people's necks.
There is no free lunch. The most we can do is force workers to trade pay for safety, which they might not want to do.
...re-balancing some of the giant manufacturing cost differential that these companies achieve by such a side-step.
The primary goal of many activists is exactly this: re-balancing the cost differential so that low skill American workers can continue to be paid well. I.e., a redistribution of wealth from Bangladesh to the US.