Why not summarize on the front, and provide more detailed information on the back? Why not? Ink is cheap.
Why not just create a brochure? If there is too much information on a business card, it is not going to be read. It may even be hard to read if the type gets too small.
If you can get them to flip it over, you're already getting somewhere. It's a useful indication of interest, but one that you won't get if there's nothing there on the back.
It can also be an indication that the person is feigning interest so that you will GO AWAY. Pretending to show an interest makes the person think they've made an impression, thank you and walk away hoping you will call.