Uh yeah. Each seat costs money and if they need two seats, buy two. If I were to want space and not have someone crowding me, I would have to buy two seats. If I wanted more room to keep my stuff, buy two seats, if I wanted room to sleep and I would like to lie down and sleep, buy two seats. It's all fair.
And it's not always someone's fault they are fat. Some people have something wrong with their metabolism they gain weight nonetheless no matter how little they eat. Some just can't lose weight no matter how little they eat or what exercise they do. It all has to do with metabolism. The most common ignorance there is about weight loss is "Just eat less food" but that doesn't work with older adults and young people with metabolism problems. Also not all fat people over eat. It's also genetic. I blame the media for causing so much ignorance about obesity. Have you ever noticed whenever you watch shows about it or documentaries, it's always about fast foods, junk food, and people not eating healthy? Plus it also has to do with food choices you make. If you eat the wrong foods, you won't lose weight. Sometimes people lose weight when they have started making better food choices. That's what happened with my husband. But he is still fat and he doesn't eat much.