Same reason Aspen trees are the largest living organism on earth. Every tree is connected to the next. If one side has plenty of water, the water will be transferred to the other side that is lacking water in the grove. That's also why they also turn yellow at the same time.Lawn marbling is what Bermuda does during a sudden onset of cool weather. It's a rhizome turf, so one "root" can grow a bunch of small independent patches (like this) or one giant mass (usually found in wild or invasive bermuda). When it turns like this, the furthest point from the nearest rhizome root starts to go dormant first because there's not enough energy/sun/warmth/etc to keep the entire plant growing. Cut off the hand to save the arm type thing. You still have enough sunlight for it to live, but not the warmth. That's why you get the oddly satisfying pattern, like marble.
When the warm temps linger like most years, a lawn will typically go dormant slowly turning brown evenly across the lawn due to a lack of sunlight instead of temp.