In many, if not most, countries before deregulation the provisions of the ITU-RR were "incorporated by reference" and thus had legal force in national law and radio rules.
This had the effect that e.g. amateur radio regulations could be quite to the point and only deal in detail with purely national subjects, such as licence classes, requirements for operator proficiency and allowed power levels.
After deregulation, many administrations got instructions not to regulate anything more than absolutely necessary, as the ITU regulations were seen by the politicians as impeding market-based decisions regarding spectrum allocation and use.
For this reason, law-makers specifically instructed the writers of new legislation and rules not to refer to the ITU-RR, so the only regulations were actually those expressly written.
This may have made telecom markets more adapted to modern business practices, but had unintended consequences for less market-oriented pursuits such as amateur radio.
It had to be specially pointed out that a radio amateur needed licences and officially recognised callsigns to operate, which the rule-makers were reluctant to do.
In their views, amateur radio was just another form of CB.
It was only by repeatedly pointing to the EU Radio Equipment Directive, in which the competence of radio amateurs is stated as the sole reason for exemptions from requiring compulsory type-acceptance of equipment and as a measure for avoiding harmful interference, that they finally budged and required an examination and the issue of a call-sign.
Currently, many of the provisions of the ITU-RR are incorporated verbatim in the FCC regulations.
This is a sign that deregulation still is quite far away in the US telecom markets.
When the FCC finally decides to deregulate spectrum access, there may be quite drastic changes to amateur radio.
One change, which seems entirely plausible in the light of what has happened in other countries, is that the FCC will finally "off-load" all licencing, handling of call-signs and enforcement matters to a third party, most likely the ARRL.