The main constraint is that you have to navigate an endless range of options, most of them bad, in every new country. It's very confusing, and you end up paying a fortune for some incredibly limited service that assumes you're going to download only 100 megabytes a month, or something like that.
Internet connectivity is less challenging than electricity
We had a lot of random problems with electricity in various places. For starters, when I'm working on all cylinders, I've got a laptop, tablet, phone, camera and other stuff all plugged in at once. I've blown out either fuses or entire electrical systems with my overuse of electrical power.
I've also experienced a lot of power failures, which are very common in some parts of the world.
In Greece and Kenya and elsewhere, many older electrical outlets have locks and on-off buttons. I've had trouble physically inserting my U.S.-U.K. adapter into some Kenyan plugs.
Finding outlets in some cafes and restaurants is nearly impossible sometimes.
Starbucks is your friend
I spent a lot of time working in "cafe culture" countries, where there are cool little coffee shops all over the place. My social media friends always lambast me for working in Starbucks instead. But at Starbucks, you can always find the holy trinity of resources for productive work as a digital nomad: Wi-Fi, electricity and a big-enough table.
In Turkey, many of the coffeehouses have tables the size of dinner plates, and chairs not much bigger. Even if you can find an outlet and Wi-Fi, a laptop overwhelms the table.
The downside of Starbucks abroad is that, unlike in the U.S., many give you a custom password that expires after 45 minutes or so. I didn't care. I just asked for five of them when ordering my beverage.
Kenya leads the world in mobile wallet usage
Kenya was one of the biggest surprises of the trip. The big carrier there is Safaricom. They sell pre-paid SIM cards everywhere, and both phone and data is cheap and flexible. You just walk in, say you want 1,000 shillings each worth of voice and data (about $12) and they hand you a SIM card that lasts for a month. (My wife got this but I didn't.) Even more shocking is that the pre-paid Kenyan SIM card continued to work fine even after we went to Europe.
Even as a visitor, my wife was able to quickly sign up for an M-Pesa mobile wallet account and pay for things everywhere using her phone.
Nearly one-third of Kenya's entire GDP is processed through mobile phones.
The ease and low cost of Kenyan mobile broadband and e-wallet service makes me think we're being taken advantage of in the U.S.
Tablets are mobile devices