Tim Culpan is a technology columnist for Bloomberg Gadfly. He previously covered technology for Bloomberg News.

Having been schooled in China, Uber Technologies Inc. looks set to be taught another lesson in Asia.

Go-Jek, an Indonesian transport and logistics startup, has a few new tricks to teach the old dog.

Its service Go-Pay was born out of a need to bridge the divide between consumers who prefer cash, and Go-Jek's mobile app that only accepts digital payments. Now Go-Pay, which is integrated into the main app, accounts for more than half of all transactions, Bloomberg News's Yoolim Lee reported Wednesday.

Go-Pay is so cool that users can even give cash over and above the amount payable to a driver, who will then credit the balance to that customer's account ready for next time -- no bank details or credit cards necessary.

Precious Little Plastic
Credit card usage in Southeast Asia is low, so digital payments represents a fertile market
Source: World Bank Global Financial Inclusion Database
Note: Data show population 15+ who used a credit card in the past year for selected Asean nations where data was available in 2014.

In the same story, Lee quotes Uber's regional chief as saying the San Francisco-based ride-hailing company has no plans for its own payments service, preferring to instead rely on outside providers. "There is no specific plan for Uber Wallet right now," according to Andrew Macdonald, Uber's manager for Latin America and Asia Pacific.

I think that's a mistake. Companies that limit themselves to single-service offerings are doomed to struggle. Exhibit A: Twitter.

I don't consider Uber Eats to be a separate service, but a different flavor of the same product, and the fact that Uber is still burning cash despite being the dominant provider in most markets in which it operates shows the fragility of the business model.

Which brings us back to Go-Jek and Go-Pay. For sure, the Indonesian unicorn is entering a crowded and competitive market where Grab Taxi, Lippo Group and Ascend Money are vying for the same mobile-payments business. I'm not even convinced that Go-Pay will be the leading player, but it doesn't have to be. All Go-Pay has to do is make life easier for Go-Jek customers and service providers and not lose money (easier said than done).

Call Me Maybe
People with bank accounts are starting to use mobile phones to make financial transactions
Source: World Bank Global Financial Inclusion Database
Note: Data show population 15+ with a bank account who used a mobile phone to make a payment or send/receive money from that account in the past year for selected Asean nations in 2015 where data was available.

That convenience alone, if well executed, should be sufficient to make the combined business sticky enough to keep momentum. Add another service -- accommodation or B2B e-commerce, for example -- and Go-Jek moves from being a service provider to a platform provider. With users' smartphone attention and home-screen real estate at a premium, a suite of services is likely to win out over just one. Exhibit B: China.

Uber's laser focus on being the leader in one specific business has allowed it to become just that. But Go-Jek is showing its larger rival that transport is only one battle in a much longer and more brutal war.

This column does not necessarily reflect the opinion of Bloomberg LP and its owners.

To contact the author of this story:
Tim Culpan in Taipei at tculpan1@bloomberg.net

To contact the editor responsible for this story:
Katrina Nicholas at knicholas2@bloomberg.net