[Tagging] How to map "piers" on land?

[Matthew Woehlke]

Please see https://www.openstreetmap.org/way/651244930. This is a pier 
with a platform on land that extends into the water. Carto cuts off the 
part that is on land.

Is this a carto bug or should the part that is on land be tagged 
differently? (I wonder about the current behavior, because pier 
structures almost never end exactly at the waterline...)

For that matter, how would something like this (a wood-surfaced raised 
observation deck) in the middle of a grass field be tagged? I've seen 
such things in some parks.

-- 
Matthew