Because of the ADDITIONAL red tape created by a law passed by the REPUBLICAN Congress in 2015 which put a requirement for an independent analysis of whether or not requiring electronic brakes would be financially beneficial to the rail industry.
The Republican law made it so that if using those brakes was not proven to financially benefit rail companies, any NEW regulation requiring them would not apply.
So even if Biden issued an executive order, it would be "trumped" by the law created by Congress.
IOW, in typical fashion, the Republithugs put corporate interests and profits ahead of human lives, public safety and the environment.
Then there were threats of lawsuits by the industry as well as opposition by Republicans in Congress.
So much for your deflection.