You are right Piglet its intended to bully rather than to persuade. They often require the RP to sign an agreement to implement the matters listed by a certain date. Unlike an enforcement notice they often contain Gold plating in addition to the key issues- often insufficiently robust in their own right that would not be included in an EN. Failure to comply is not an offence but signature then places the RP in a difficult position later if an EN is issued. I think they, along with plea bargaining are a travesty of justice and way outside the provisions of the enforcement concordat.
Although I am generally of similar opinion to the fire service with regard to technical and managerial failures to comply, if asked I always used to advise RPs to have nothing to do with them. If the IO cannot persuade the RP to see the error of their ways through information and education then if concerned they should issue an EN and give the RP the legal right of appeal.