is the number of spotters ruled or it's just up to the organizer of the meeting?
2 - 5, with 3 being the average on regular lifts. But you could call for 5 on a very heavy lift. And of course if there is an accident, everyone can rush in.
For squat, a lot of the federations are adding safety straps like this in addition, that are set below parallel, but still can catch the bar -
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For Bench, the moves have been slower, But some, most notably the IPF / USAPL, have started using safety stands -
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The biggest thing is money and time. Most meets are small time things, so the directors don't want to buy and move new gear. They also don't want to have to adjust the equipment each time to fit a lifter when many meets are almost all day things.
There are also arguments that it would affect judging, photos, etc....