There are two kinds of poverty in Germany, maybe even three:
1. The people who, due to psychological or other circumstances, fall out of the welfare systems: people losing their jobs and subsequently homes and due to lack of a social net to pick them up and an inability to contact the authorities to push through welfare applications end up homeless and, if they were not already before, drug-dependent and/or mentally ill as a result. These are the people you see begging for money on subway trains and street corners.
2. Welfare recipients: Due to the bad design of the "Hartz IV" welfare system and the unbelievably low monthly payout (try living off 382 Euros a month, with no extra money to replace broken household appliances/buy clothes/etc), Hartz IV may enable you to survive, but not to live. Additionally, keeping the "Job Center" happy so they won't cut your payout for being a suspected freeloader is almost a full-time job, reducing the time you can spend actually looking for a job. To make matters worse, you can't just opt out of Hartz IV anytime you like: You have to prove that you secured a stable income. If you just got a well-paid freelance gig for a month that will enably you to get by for, say, the next three to four months, they won't let you off the hook, but take 90% of your paycheck as a payback of the welfare money you received and you'll stay on welfare, thank you, next in like.
These are the people who you'll see collecting bottles.
3. The third group could be integrated into the second: The working poor. More than a third of Hartz IV victims recipients are actually working half or even full time in some shit service industry job that pays them less than their Hartz IV payout would be, so they get a partly Hartz IV payment in order to get by. This mostly affects single mothers.