Not all seeds in all animals. In fact, some seeds are adapted to different animal digestive systems. The chili peppers I mentioned, for example, reliably survive a trip through the bird species that typically eat them but can be destroyed by many mammalian guts.
In some cases the seeds need protection to survive a trip through a gut. Cows, for example, have quite the digestive system which involves several grinding steps, soaking in acid and enzymes, and quite a bit of time. Any seed that needs to survive that gauntlet will need more protection than something taking a trip through a chickadee. Elephants will swallow whole seeds and nuts you or I need to crack open and take apart. Trained science types can make a good guess as to the size and type of critter that is “supposed to” eat a fruit or seed based on a size and outer covering.
Other seeds have protective layers to survive harsh environments (like coconuts) or require some stimulus to be released, such as certain pine cones that require exposure to fire before they release their seeds.
Most are “targeting” a specific group, and as I noted with the chili peppers will also sometimes have traits that discourage other groups from eating them.