It largely is. That is, globally peanut is among the most common severe food allergies, but it's still fairly rare. But in the developed world (IIRC, particularly the US) popular guidance to mitigate the risk of peanut allergies in very young children (who can't communicate symptoms.as effectively, so, if they have an allergy, are at greater risk of consuming more and/or having treatment delayed) was to avoid any exposure.

It turns out that that guidance actually increased the incidence of severe peanut allergies immensely, because it made it much more likely that when people were exposed later, they would develop an allergy, and peanut allergy is far less common where children are usually exposed at a young age.

Yeah, disease of affluence, they call these things:

https://en.wikipedia.org/wiki/Diseases_of_affluence

It's weird how acknowledged the problem is in the US (and Europe?) and how rare it is elsewhere. Trying to convince people in certain countries that peanut allergies are real can be really difficult, because they have never heard of such a thing. It's also even hard to find information online about the worldwide prevalence of peanut allergies because almost all of the data is US-based, with the occasional tidbit from the UK or continental Europe.

There's something called the Hygiene Hypothesis which states that "a lack of early childhood exposure to infectious agents, symbiotic microorganisms (such as the gut flora or probiotics), and parasites increases susceptibility to allergic diseases by suppressing the natural development of the immune system".[1]

In other words, it could mean that excessive hygiene in childhood could be causing allergies.

[1] - https://en.wikipedia.org/wiki/Hygiene_hypothesis

Quite likely - some of the more recent thinking is that it is linked to a loss of gut bacteria - which makes sense for our case as our boy had antibiotics young, and first reacted to nuts at 4 months.

India does have a huge problem with lots of people dying from poor food (and other) sanitation practices, though. When your house is burning down you don't notice a light left on in the attic.

Possibly. Or the people who have it just die for unexplained reasons.