> "i always ask myself what the value proposition and applications for such maps are. It seems like they take large resources (e.g. manual collection of the data) to create"

There was a survey a few years back to assess the economic value of the trees in London, for pollution removal, stormwater alleviation, etc. which put the total annual benefits at £132.7M[0].

[0] https://www.london.gov.uk/sites/default/files/valuing_london...