The UK uses the trunk tag differently from the rest of the world. In most of the world it implies bicycle=no and pedestrian=no but in the UK it implies bicycle=yes and pedestrian=yes. You will see old acknowledgement of the issue going back to 2008 on the talk page for the tag, but people have just lived with it. The UK tagging of single carriageway, open access roads as trunk routes is not incorrect in the sense that in the UK these roads are known as trunk routes even though they may be relatively minor roads.
As a cyclist this causes me grief as although there are UK specific producers of Garmin maps, they have issues and I would like to use alternatives of which there are several produced by European producers. Sensible routing on non-UK derived sources is impossible and in the past, I have been told that the map producers will not change their automated routines to do something different in the UK.
There are two obvious solutions to update the source: to implement a new tag across the UK which acts as a trunk tag but is simply a different tag (e.g. trunk_uk), or alternatively perform a countrywide attribute replacement where the UK default attributes of bicycle=yes and pedestrian=yes are explicitly set. The first one would confuse existing producers but an easy tweak to adopt, and the second would be transparent but require a one off update and there is the possibility that new routes would not be maintained correctly (but how often are new major trunk roads created).
Not knowing how I would get agreement on either of these matters, how would I go about this? Secondly, if a one off update was agreed to be the correct approach, how could I get someone competent to do this?