I often think this with respect to sewage spills from water co’s. If Thames *is* renationalised, the pollution doesn’t instantly stop and it’s no longer “sufficient abstract evil shareholder” to blame it’s literally the government. Do you really want to touch that 3rd rail?
It is worth remembering that one of the reasons public utilities were privatised originally was to depoliticise them and help politicians avoid blame for poor service. Nationalisation may be popular in the short-term, but there are longer-term risks of assuming responsibility for service quality.