The poverty line is set too low, but also, things like living wage thresholds are often (but not always) calculated on the assumption that there are two working people in a family. Which is often not the case.
Also, employment is becoming increasingly more precarious, with people either not getting enough hours, or not getting enough money per hour, or short fixed-term contracts, or short term gigs, which make it difficult for people to prepare themselves financially for economic shocks and other unexpected financial stressors. Meaning for a lot of people, it only takes one unexpected shitty thing to happen, to take them from making it day-to-day, to not being able to afford the next grocery shop.
The problem is, once people get into poverty, it is a vicious cycle and very very difficult to get out. It literally changes the way you think. I was born into poverty. It took me most of my life to get to a point where I wouldn't consider myself poor. You just don't even get as many opportunities to get rich, when you're born poor.
Poverty sucks, and is bad for everyone, including people who are not in poverty.