My understanding is that lower fertility follows higher female education for several reasons, including that women in school - and with access to birth control - prefer to wait until finishing school and starting a career before having children. Countries where women have fewer educational and fewer career opportunities, people often start having babies sooner, and more babies overall.
Another oft-mentioned factor is social safety nets such as social security (as much as that can count as a safety net). Areas with no or weak elder support outside of the family tend to have bigger families. Shockingly, this was also the case in the "developed" world back before they developed. Ask older adults in the USA how many brothers and sisters their grandparents had and it is probably a lot more than the next generation had, and the next, etc.
Do colonized people have lower life expectancy or do their children? Or both? Certainly, exploited people may also be living in (and unable to escape from) a society with poor elder care and insufficient safety nets such as social security or other retirement options. Which, of course, makes having lots of kids a totally rational decision. And also limits the ability of many women to participate in the economy outside of the home, which can also slow the development of the country / area's economy.
I left Japan in 2008. Phones had had cameras long enough that the makers had to add the can't-turn-it-off shutter sound because so many chikan were taking upskirt photos on public transport.
Less salaciously, there was also panic about people taking pictures of magazine articles in bookstores and then not buying the magazine. Not sure anyone really would have tried to read an article on those tiny screens, though.