Most prams I see these days are much larger than the simple, light-weight folding models many people had when I was a child in the 80s. They're basically monster-truck-prams.

I think the perceived comfort, safety, and luxury is a big drawcard in both cases.

An American who lived in Europe started a business importing luxury prams into the US:

https://www.theguardian.com/news/2018/mar/20/bugaboo-luxury-...

Having pushed my share of prams, larger diameter wheels are a plus. But my favorite one for convenience was a folding "umbrella stroller" that I could shake open with one hand while holding a baby with the other.

I have a Britax Pathway stroller (https://www.target.com/p/britax-pathway-b-safe-35-travel-sys...), which looks like a monster, but literally push one button and the thing deploys; I did it several times today with the baby in the arms.

As well as the reasons you mentioned there is also perceived value for money. I suspect this trend is due to an interaction of psychological marketing and consumer preference.

Prams / strollers are not car seats.

Some places require kids to be in car seats until age 8. This is 2nd, 3rd, or 4th grade. These are not babies.

The manufacturers have lobbied for this "think of the children" law. Sales go up because parents are forced to buy the product. The manufacturers would be happy to raise the age even more.

1% of those kids are over 92 pounds. One can outweigh the mom, and can be asked to install his own car seat.

Maybe I'm missing something super-recent, but for second graders, a "cat seat" is basically a piece of plastic for them to sit on so that the seat belt passes on their chest, instead of neck, which would be disastrous in case of accident.

Unlike toddler car seat, these seats don't look huge by any means, compared to the kids sitting on them. (Well I guess it's still problematic to sit three of them in a row in most cars, but that's a separate discussion...)

The author of "Freakonomics" has a TED talk about this. It's a little old though (2005): https://www.ted.com/talks/steven_levitt_surprising_stats_abo...

Fear is not only the mind-killer, it's also the most powerful upselling strategy in the world. Particularly to young parents who tend to be a bit insecure about how much caring is enough. It's not just fear that something bad might happen to their child, it's also fear of being only the second-most responsible set of parents in the room.

Mostly safety because there is more focus on side impact protection. it leads to wider, wrap around designs.

I believe it is because they’re made of plastics which need more width to provide the same strength.

The narrower seats (I used Radians) all appear to have metal frames instead. And they weigh more!

I instinctively thought of high obesity rates in the US and other western nations.

For babys?

As others have said.... many jurisdictions in the US now require child seats well into the elementary school years.

Mostly boosters though, which aren’t really full fledged car seats. Washington requires car seats until 4 or so, and boosters until middle school.

It's for kids who haven't yet reached age 8 or a height of 4'9" (145 cm). That is the law. They could easily weight as much as their mother.

Washington state just changed their law. Now kids under 4'9" must use a booster up to the age of 16. Realistically, they have stated that 13 year olds will not be required to use a booster since, at that age, they are allowed to sit in the front seat anyway.

For a single seat, the size makes sense as you want to have cushioning on the outer walls. But there is no good reason not to have double and triple seats which only has thin separation on the inner boundary of the seats (even just having once the default padding vs. twice would be a big win).

So, if car manufacturers want to advertise "3 rear seats", they should be forced to offer child seating for 3 too.