They are homeless not Amish. People can have jobs too while being homeless, since you often can't afford rent in many parts of the world with just a single income. You have to choose between a roof over your head, or eating and having a car to be able to go to work. Or you can get a second income, either another job or a relationship, but that's not always an option, hence why so many people live in their cars. Around 200,000 people live in their cars in the United States alone, but that number is climbing rapidly and will reach a million in a few years, because housing is a luxury now.

And just to compare, the cheapest completely useful (4G, 3GB RAM, 3000mAh battery, Android 11) smartphone is $30, the average monthly rent of a two-bedroom apartment in the United States is $1300.

Most homeless people aren't permanently homeless. Of the homeless population at any given time (very) roughly 50% will only be homeless for a few days, 20% will be homeless for a few weeks, and 30% will be homeless for months or longer.

I was walking to a convenience store two nights ago and I saw a girl venmo'ing a homeless man money. Realistically it's hard to exist without a phone and bank account, and there are a lot of financial aid/benefit programs for homeless people to pay for these sorts of things