Two anecdotes perfectly explain why it's so hard for Google to build products for billions of people

Google's scale is unparalleled.

There are now more than 1.4 billion monthly active Android users, while its core search business racks up an astonishing 1.2 trillion searches every year. It operates in just about every market in the world (with the exception of mainland China, although that may soon change.)

And with this size, comes some serious difficulties.

At the Web Summit tech conference in Ireland earlier this month, we sat down with Aparna Chennapragada, a director at Google. We discussed her work building Google Now - Google's virtual assistant that tries to proactively provide useful information to help users go about their day.

Chennapragada shared two anecdotes that demonstrate a key challenge for Google: Accounting for the wildly varying needs of its disparate users around the world.

Mumbai trains and private jets

First, she highlighted a feature in Google Now that helps you remember where you park your car: "Awesome feature, everyone in the Bay Area who has parking woes, they love it." But a user study carried out in Mumbai, India, provided a "reality check."

A Google researcher explained the feature's possibilities to a user in Mumbai, "and the guy just stares at him for a while, and says: 'I jump off a train every day.'

"I'm laughing now, but I was like 'holy sh*t!' We really need to figure out what works for different markets."

Later, she provided another example - again from the car parking feature. "So we got this bug - and I'm not saying this is a normal bug - but we got this bug from a bug report." And the report says "'Hey, I just got off my jet, and you think I parked my car' ... And I was like 'that's not a problem for most of our users!'"

It's the total opposite end of the spectrum - but demonstrates the wild variance in use-cases when you operate on a scale as large as Google, and the subsequent problems you will face.

This isn't a problem unique to Google. Also at Web Summit, Facebook's head of security David Stamos touched upon the unique problems that "huge diversity" in users can produce. It's about "trying to build products that foresee issues that never appear to us in our nice air-conditioned offices in Menlo Park," he explained.

"I'll give you the honest picture here,"Chennapragada told me. "when we give [users] assistance for enough points during the day or week, [they] find it super useful ... [but] what we do find is in certain markets and certain users ... [we don't have] many useful things to say yet."

She continues: "It is a challenge, right - do you change the product entirely to fit one market, [or] do you basically say: 'No, these markets will evolve into the high-end market'?"

Such are the dilemmas you face when operating the same products in dozens of different markets with differing social and economic contexts.

Assistance is just getting started

Chennapragada suggested that the hardware in modern smartphones can still be a limiting factor in what is achievable. "I mean seriously - it gets it wrong, the train versus the parked car ... The hardware signals are not yet there.

"We could go really invest a lot more in sensors and ten get there, but given battery life, and where things are, it's not really so wise. So we said, you know what, we'll try to make this work with x-percent of accuracy and we live with that."

Is the vision for mobile ahead of the reality? "Not specific to Google Now, but any of these things, when we say this 'contextual computing' as such, there has to be innovation all through the stack."

Virtual assistants are a hot trend in tech right now: Competing with Google Now there is Apple's Siri, and Facebook offers M. "I think we underestimate where we are in the cycle of the whole assistant-based [app], " Chennapragada says. "On demand is all the rage right? ... Asisstance is like opinions, everyone has them. The parallel for me is the 1990s web - it's just getting started ... There's an order of magnitude more users, 5 billion people will be online in fice years, and suddenly this actually has the ability to affect the real world ... we want to make sure that we're building the blocks right."