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Access restrictions in OSM, like the bicycle=* tag, apply to legal restrictions. In the UK, use_sidepath does not apply as cyclists use roads by absolute right (unless explicitly prohibited by a traffic order with accompanying signage). In some other jurisdictions, cyclists are required to use a cycle track if provided, which is what this tag conveys.

The tagging on this section of Prestwick Road which would describe the situation is cycleway:left=separate + sidewalk:left=separate (left is in relation to the direction in which the road was drawn in OSM).

https://wiki.openstreetmap.org/wiki/Tag:bicycle%3Duse_sidepath
https://wiki.openstreetmap.org/wiki/Tag:cycleway%3Dseparate