I disagree. There are families out there that have 1 child and little materials, and some with 7 children and everything they set thier eyes on.
Just becasue a family is large does not mean that anyone is in lack. I think you're questioning economics more than anything - and differences in perception and parenting.
It appears you feel money and accessories are most important in family life. I could be wrong, but I'm basing this assumption purely on what you have written, being that i have no other information.
However, there are many others out there that believe money is an addition or a bonus to the things that can be provided that cannot be paid for through financial means, such as morals & values, love & respect, compassion & understanding, etc.
Some feel that an abundance of materials contribute to the "spolied rotten" mentality and lead to selfish behaviors. But you may not see it this way.
I believe it has more to do with the things we instill in our children, regardless if they have a smart phone, ipod, tablets, pc's, and numerous other materials. You can take a child that has little belongings, but with adequate parental love, emotional & educational support, and morals & values instilled in the child through proper parenting, they can lead very healthy and successful lives. (Pres. Barak Obama is a living example.)
On the other hand, there are many children in the world that have every material thing they've ever asked for, and do nothing with thier lives - no social or economic contribution what-so-ever.
Again, I believe there's a lot more out there than just buying a child everything they ask for. Currently, I don't make a boat-load of cash in year, but my children are blessed abundantly in so many other ways. They are well-behaved, gifted/advanced students, they are loving, compassionate, respectful, loyal, wise, musical, artisitic, humorous, and so much more. I'm grateful that they have learned to value life and each other, more than placing value in belongings.
Just thought I'd give my opinion as a mother who has a number of children somewhere between the 2 & 6 you offered as examples - I'm also not poor or rich. I care more about thier spiritual, emotional, mental & physical well being, than I do about how many things they've acquired. I'd rather my children have more of what they can feel and less of what they can touch, rather than the other way around...