Galleries and museums are different animals.
Museums, even contemporary art museums, generally require the exhibition to have some degree of historical value, or a bold statement about modernity.
Galleries are wide spread in their requirements, and many specialize in particular mediums. A sculpture gallery isn’t going to be prepared for a photo exhibition.
Is it a top tier gallery? They’ll only show artists that have attained some degree of fame with a long list of past exhibitions under their belt.
If you don’t have past exhibitions under your belt, then presenting an idea won’t carry much weight. You may need to produce the work, and then shop it around, or have it tied to a publicity campaign to get attention you seek.
Photo exhibitions are often found in eclectic neighborhood photo studios that throw monthly parties and exhibit out of town photographers. They’re also seen in many coffee shops and speak easy’s, martini bars. No curator means open standards. Photo exhibitions are also very popular with the art fair circuit. But the best fairs have strict admission requirements and charge fees to participate. Those who make money at it have a routine with traveling gear and display mechanics worked out.
Art is a business.