The wiki provides a reasonable description of a rest area, however extending that to a layby is going a bit far.

In a layby you are unlikely to get toilets or picnic tables, although you may get a bin if you are lucky 

For some reason the UK never did proper rest areas, as you find in France, where an area similar to that of a service area is provided with just parking, picnic tables and toilets.
These are away from traffic where you can sit and enjoy lunch. My girlfriend and I choose these when traveling in France and take a picnic with us.
https://www.openstreetmap.org/#map=17/46.15857/1.37807

https://mapillary.com/map/im/312447120374092

Mapping laybys, such as this as rest areas is very misleading. If mapping them as areas they should be tagged as amenity=parking.

Cheers Phil
