Those black streaks running down your shingles are a bacteria called Gloeocapsa magma. It lives on the limestone filler in asphalt shingles, and damp coastal air is close to ideal for it.
Asphalt shingles are protected by a layer of mineral granules. Pressure strips them, and once they are gone the shingle is exposed and its life is shortened. A roof cleaned with pressure can look excellent for a season and cost you years.
Roof work is therefore soft wash only: low pressure, the right solution, and patience. The streaks lift and rinse away, and the roof is not aged in the process. Shingle manufacturers say the same thing in their own warranty documents.
Moss holds water against the shingle and lifts its edges. Lichen roots into the surface and leaves a mark even after it dies. Both need treating rather than scraping, and both are worth catching early, because neither one is purely cosmetic once it has taken hold.
Asphalt and architectural shingle, standing seam and corrugated metal, cedar shake, and terracotta or concrete tile. Pricing is by roof area and pitch, since a steep roof is slower and more careful work than a shallow one.
Prices are on screen in the estimator, and nothing is due until the work is finished. Book the date yourself when you are ready.