I suspect it’s related to a lack of immediate cost to the largest companies.
Derailments are still infrequent enough that the company can be insured against the losses, so if derailments happen, there’s effectively zero cost to the company.
That would change if this class of train made incidents so frequent that insurance companies were no longer willing to sell insurance for derailments incidents involving this type of train. At that point, they’d be phased out of the fleet (as they crashed out of service) and then individually written off as a tax-deductible loss.
Derailments are still infrequent enough that the company can be insured against the losses, so if derailments happen, there’s effectively zero cost to the company.
That would change if this class of train made incidents so frequent that insurance companies were no longer willing to sell insurance for derailments incidents involving this type of train. At that point, they’d be phased out of the fleet (as they crashed out of service) and then individually written off as a tax-deductible loss.