During the drafting of the parking=street_side proposal this tag was one of the existing parking=* values that lacked most in documentation. Yet with over 10,000 uses it is very much in use.
I have gathered here what is known about this tag, and how it is effectively used in the interest of providing some clarity on its and other parking=* values. — JeroenHoek (talk) 17:45, 2 December 2020 (UTC)
Is parking on a lane always parallel? See example: https://polska-org.pl/9675787,foto.html (pay attention to the road sign) where the street is wide enough for cars to park perpendicularly. So is it parking=street_side + parking:orientation=perpendicular or parking=lane? maro21 16:01, 23 January 2022 (UTC)
Regarding this tag being seen as controversial
This edit (since reverted) inserted a section that declared this tag controversial. This is a bit extreme and not in line with how this tag is used. This tag is used over 37,000 times and can be used there where explicitly mapping parking lanes makes more sense than using the parking:lane=* on the highway. Examples include oddly shaped lanes or streets where parking=street_side is used as well, and sticking to one scheme makes the whole easier to maintain. There are more valid uses, but those alone should suffice. There is no real controversy here, just personal preference and practical limitations. That is, often using parking:lane=* instead of explicitly mapped lanes is preferable, but that does not make this tag controversial.
The How to map section already includes a note about how this method can be seen as a form of micro-mapping, and duly links to parking:lane=*. --JeroenHoek (talk) 14:56, 28 October 2022 (UTC)
Note also a major rework of the parking:lane scheme currently in progress, which explicitly refers to the separate mapping of parking geometries and suggests in which situations this tagging can be useful, even if parking in general should rather be captured at the street centerline. --Supaplex030 (talk) 15:03, 28 October 2022 (UTC)