Around here at least it seems to get used both for "bikes not allowed" and "this is a busy road so we're avoiding sending bikes here".

Where I know the roads, I'll occasionally be on short stretches of pink because while discouraged it often is a more direct way. For example, below is a Google Street View of a short section of road in Buda, TX that was marked pink. It is two lanes, no shoulder. However, bikes are allowed and I needed to travel 1/4 mile to the light at edge of the picture. I was on it the weekend before last because it was straightforward and direct. As the population grows in this area more roads that I've been familiar with traveling get marked as pink.


In areas where one is not familiar there might be no specific reason to ride the pink roads so that is fine. However, it can also be an opportunity to check out a bit more with street view or a heat map.