Much that has been discussed is ok for "Hobby" or home type machines.
As someone that retrofits drives and controls fora living I yet to hear much about the real world issues of safety and "Safety Standards".
The attached link is a 5 axis digital drive I completed last week and every possible safety issue has been adressed.In large gantry machines like this, all axes drive motors have brakes to ensure a quick stop in an error condition.
Soft over travel limits are set and deal with normal overtravel condition and extreme overtravel result in a complete drive shutdown.
E Stops are handled by relays designed for this purpose.Not being critical but none of this would work in any real world manufacturing plant.