If we look at this logically, requiring/expecting all possible safety improvements on every aircraft makes no sense. There needs to be some cost/benefit analysis of potential options, and different carriers could well evaluate this differently or have different needs and different flying patterns as well as realistically different levels and types of pilot training/experience/judgment. In the case of aircraft, weight is also an issue so that if something that marginally improves safety adds a lot of weight to the aircraft, adding the option might not be a wise decision. Let's not forget that airlines need to make money or at least not make consistent losses unless they're subsidized by some government or other entity.