Not really, it's just that we find it difficult as adults to empathize enough to understand what's bothering them. Children cry because they're hungry, because they've got gas, because they're sick or uncomfortable, because they're overstimulated, or because they're bored. Since they eat every few hours, have developing digestive systems, have developing temperature regulation systems, and have no internal monologue and short attention spans, one of these things becomes a problem very frequently.
As they get older, they cry because they have no emotional regulation (something that isn't fully developed until after adolescence). If I snatch a candy bar out of your hand you were about to bite into, you feel that initial pang of loss but quickly your higher faculties regulates that emotion. If I grab a piece of "floor food" my 9 month old is about to put in her mouth, she feels that same emotional response, but there is nothing to regulate it.