Why Does Regine Velasquez Always Sing Mariah Carey Songs?

Okay so I found out about a Filipino singer named Regine Velasquez, when I was looking at some Mariah Carey videos on YouTube. There were all of these videos of her singing Mariah Carey songs like, "Heartbreaker", "My All", "Butterfly, and "Emotions". She also covers other songs like, "I Don't Want to Miss A Thing" by Aerosmith, and a lot of other people's songs. I've never heard of a "professional" singer who can get away with singing everybody else's songs. In my opinion, she has a nice voice, but the songs that she covers, particularly Mariah's, don't compliment her voice at all, and she sings without emotion! Personally, it bugs me because I like true artist, who write their own material. It doesn't bother me that singers does covers, but it bother's me that she constantly does covers, all the time! So I was wondering why Regine sings other people's songs so much (mostly Mariah's)?