Why do the carriers put limits on data instead of a higher unlimited plan?

[AlphaDroid]

Why do the carriers put limits on data instead of a higher priced unlimited plan?

Why do the carriers put limits on data instead of offering a higher priced unlimited plan? Are they afraid that you will intentionally clog up the data available for other customers by abusing the data, or slowing down other users because the present system cannot handle the loads...?

Why does my Motorola Droid smartphone have unlimited data on Verizon but not the Galaxy?

 

[New2u]

Why do the carriers put limits on data instead of a higher unlimited plan? Are they afraid that you will clog up the data available for other customers...?

Why does my Motorola Droid have unlimited data on Verizon but not the Galaxy?

Verizon has stated already, whether it's 100% true that they are moving towards tiered data, now some think that the unlimited will be an option but for more money and some think it will go away all together. Not offering unlimited data on tablets is a very strange concept to me.