Only the manufacturer gets feedback on the fate of all its aircraft. Your fleet may have 50 of them and learn much from that, but the manufacturer made every single one. They may not have the operational experience, but they do learn and intensively study every single accident. They issue their manual on the basis of all this accumulated experience and it seems strange that deviations should be allowed. I can easily see how this has arisen historically, but I would be genuinely interested to know the type of operational demand would require a change from manufacturer's recommendations that could have safety implications. (Granted the TOWS check was recommended by Boeing and not mandatory).