I’m sorry it doesn’t make sense to you. If you’re interested in learning more, I recommend reading up on the old auto trails in North America to understand how the concept of a marked route developed. This concept subsequently spread to other regions, including Australia. Even in the United Kingdom, which only numbers roads and motorways, there is a formal concept of a “primary route” that laypeople experience as green-and-gold signs bearing the component roads’ numbers.
I think you’re reading too much into the wording of a dictionary definition as if it’s an OSM tag definition. Dictionaries generally do not provide the full context as other reference works, such as the ones I’ve cited.
I wonder what you think a bicycle route is, since bicycle routes routinely travel over multiple facilities, including on- and off-road segments. Is it so unimaginable that the same concept could normally apply to vehicular travel as well, if not in your country then in others?
Even though I haven’t convinced you that routes and roads are orthogonal concepts, you have acknowledged my main point: roads and routes are not synonymous. Therefore, we should err on the side of precedent and backwards compatibility by sticking to the longstanding usage of route=road for highway routes (or “on-road routes” if that’s clearer) and finding some other tagging for relations representing a street per se. It doesn’t have to be type=street.
Some 70% of these local roads have ref. Does this mean there’s some kind of systematic designation and marking of local roads? If so, it may be similar to the county road “routes” I described earlier, in which the main reason for conflating roads with routes is to enable renderers to distinguish different road networks’ distinctive shields. It’s a pragmatic approach but technically inaccurate. There’s an ongoing debate about whether to apply this approach to forest roads in the U.S.:
Even at the city level, it can be conceptually useful to distinguish between streets and marked routes. Maybe someday we’ll get around to creating relations for the streets of Fremont, Ohio, but they should not be tagged identically to the city routes that guide motorists along those streets. With the thousand or so different values of network now being used across the U.S. to represent marked highway routes, I wouldn’t want data consumers to have to know the difference between network=US:OH:SAN:Fremont and network=US:OH:SAN:Fremont:but_not_actually_a_route.