Toddlers sing along songs, kids like hearing the voices of kids, so these songs really appeal to them.
Children learn the lyrics from the music they hear, weather in the home or traveling in the car. What lyrics are they hearing and words are they learning ? The right music can calm an upset child. Hearing the same songs help them to remember the calming lyrics when they are having a bad day. Try substituting your music for this music while in the car, and watch the fun interaction they can have with the right kind of music.