Baby sea turtles can't really orientate themselves, so they just instinctively move towards light. Normally what they'd first sense would be the reflections of the moon and stars across the ocean's surface. The problem is that humans have created many artificial light sources that are way brighter than mere reflections.
Along almost any coast, you'll be able to find either hotels, restaurants, bars, and even homes. If that wasn't bad enough, there still might be streets and or streetlamps which could easily attract baby turtles. Those moving balls of light are definitely fatal for most lifeforms including baby sea turtles.
Most sea turtles that end up lost on land don't have a happy ending. For example; imagine what would happen if a playful child found that baby turtle or maybe a dog/cat.