I think it's okay to make the "x sharing" link that small for two reasons :
- Some people doesn't really like the idea to share their taxi with unknow folks
- This is first of all an information, not every users care about who is sharing their taxi and nor would click on the link
But if your goal is to increase the social part of the app you could make it visually bigger or try to display the user's profile picture directly on the first screen.
download bmml source – Wireframes created with Balsamiq Mockups
I don't think the second screen is too cluttered. Actually it's well structured with all the informations. You did a great job !
P.S.: I'm wondering if it is really important to show how much the others are paying for the taxi ?