True, but the cost for a data plan is expensive.Not all of them. Plus if the phone is a gift the plan may be a part of it, I pay my brothers phone bill as he couldn't afford it on his own and it's worth it to be able to contact him.
I know of at least one case where a homeless and drug-addicted family member's parents paid for his "fancy and expensive" (not really) phone and data plan, so he could be in touch with his sponsors, work, and so that they could check in with him regularly and find out if he was alive or dead on any given day.
Please, people, give up the idea that if you see someone with what you perceive as an expensive piece of technology, that it indicates they are moocher/scammers and not really in need. Technology can be produced and repurposed so inexpensively these days, and it's not unusual for certain charities to help a homeless individual get a second-hand laptop or discarded cell phone so that they can attempt to find work or stay in touch with their family. Many places of employment or social services can't do anything unless they can register a phone number and/or email address where they can reach you.
This is like the complaint that "99% of welfare recipients have refrigerators!" Er... in most states, it's illegal for parents to NOT have a way to keep and preserve food for their families long-term. It's hardly an indicator of frivolity.