Hi all,
I strongly agree with JackieDe. Automatic crop is standard for many photo editors.
I use Affinity and Serif as my main programs for editing and layout jobs but I don't use Affinity for photo editing when it comes to hundreds of photographs I've taken – because of the lack of automatic croping. In this cases I switch over to programs like Nikons Capture NX-D (my favorite prog for mass editing), Photoshop Elements, Photoline or others which are capable to crop images to transparent areas automatically (and there are a lot).
Sorry, but Affinity Photo does NOT serve fast mass photo editing, and also the macro solution has some more clicks to apply it to the image (even if it works well).
Cheers, Ludger