galvanized metal roofing, durability?

[BlackAkita]

My reading of how Aluminum and zinc protects the steel or iron base of the roof tells me if the top layer wears away or is scratched off, then galvanic corrosion can occur. The other two substances it needs are an electrolyte (ionized water) and an unfriendly metallic element.
https://www.atas.com/wp-content/uploads/...FINAL2.pdf
Everything wears away eventually, including acrylic coatings. I hope the birds will not poop on the roof, or claw away at it.