There's a fairly long list of coincidences necessary for someone to accidentally or intentionally come up with this same image - position of sun and clouds, wind/water conditions, season, the sailboats
So the circumstantial evidence is incredibly strong, and the number of discrete elements that differ are few. (The sailboat seems a bit small in the photo, so enlarging it makes sense - moving the sailboat closer to the foreground might have made even more sense, as the diffuse reflections in the original that add interest to the foreground are not present in the painting. If I was a conspiracy theorist, I could imagine that the artist was instructed to duplicate the photo, and therefore did not stray overly far from the composition.).
Does it matter whether a road or trail is nearby? The painter could argue that he/she hiked the distance anyway. Then, try to disprove it. "Yeah, I was inspired by your photo to travel to Lake Windermere to try to duplicate the circumstances." "Show me the travel receipts!" "I used a 3D mapping and rendering program to duplicate the conditions." And so on. A tough, probably expensive process, that may yield neither justice nor a finding of damages sufficient to meet the expense.
I'm tempted to suggest forging some sort of alliance that works to your mutual benefits, rather than an adversarial relationship, but I tend to be kind of utopian in that regard.
Yes, it's possible to take photos of Half Dome that are incredibly similar to some of Adams' - who, presented with the opportunity, hasn't tried? There are many, many other Adams images that would be near-impossible to duplicate - moon in a particular phase and location coupled with the position of the sun necessary to cast the requisite shadows, proper cloud conditions, snowfall
it could take many years of patience and planning, plus a huge amount of luck, to ever come close. "Winter Sunrise, Sierra Nevada from Lone Pine" is a fine example.
That's why most of us focus on applying Adams' aesthetic and techniques, rather than slavishly duplicating particular results. That's the difference between "in the style of," and outright copying.