SAN JOSE, Calif. — Perhaps the biggest question swirling around this week's Finovate conference is: why are mobile payments still more hope than reality?

And that raises a second question: are tech investors smart to continue pouring so much money into mobile payment startups?

Nearly a dozen companies are presenting mobile payment technology during the two-day financial technology conference — tagline: "Where Silicon Valley Meets Wall Street" — and that list doesn't even include big players such as Google, Square or PayPal.

The companies that are showcasing their technology here seem intent on demonstrating that they grasp the key reasons why, despite years of hype, mobile payments have yet to really take off in the United States.

These firms are emphasizing their practical virtues: the value they can provide to everyone in the existing payments chain; the simplicity of their products; and the specific problems they are trying to solve for retailers, financial institutions and consumers.

"If you're solving a real problem, they're going to sign up in droves," argues Wendy Keith, chief executive officer of Toronto-based Digital Retail Apps.

It doesn't save much effort for a shopper to scan a mobile phone rather than swiping a credit card, which may help explain why U.S. consumers have so far been underwhelmed by mobile payments.

Keith's company seeks to eliminate a legitimate hassle for many shoppers: waiting in the checkout line. Her firm's app, called SelfPay, allows customers to scan a bar code in the store, click on their phones to make the purchase, and then walk out of the store with their merchandise. The merchant quickly verifies the purchase as the shopper leaves the store.

"With SelfPay there is no line, so you can just keep shopping," Keith told the audience at Finovate. It was a memorable line, but the company's technology remains young, having only been tested on a small scale so far.

Sunnyvale, Calif.-based Quisk has been focused mostly on mobile payments in developing countries that are much more reliant on cash than the United States is today.

Quisk is now looking to enter the U.S. market, but Chief Marketing Officer Dan Glessner acknowledges that finding a compelling value proposition is trickier here than in many other nations because the existing U.S. credit and debit card system generally works well.

"It's harder to get people to change from something that's really easy," Glessner says, "unless you have an alternative solution that is a quantum step up. It's got to be much easier."

Quisk is marketing simplicity as a key advantage of its mobile payments offering. That's a selling point both for retailers, which can receive mobile payments on their existing point-of-sale terminals, and to consumers, who can send text messages to make their purchases.

Quisk is hoping to sell its mobile payments product to U.S. retailers that have a stream of regular customers, and could use it to build a loyalty program.

But Glessner acknowledges that the tipping point where mobile payments get broad adoption in the U.S. doesn't appear to be right around the corner. "Candidly I think we may have a ways to go," he says.

Other companies that made presentations Tuesday in San Jose were also focused on finding that elusive set of benefits that will finally provide sufficient incentives for retailers and consumers to use mobile payments.

Fremont, Calif.-based MShift demonstrated its AnyWhereMobile Payment network, which it's planning to roll out in gas stations. MShift pitched its system as a win not only for consumers, who will get discounts of 10 cents a gallon, and gas station owners, who will save on interchange fees, but also banks, because their lost interchange revenue will be offset by reduced processing costs and fraud losses.

But mobile payment companies presenting at Finovate face a more skeptical audience than they did in the past. Everyone seems to realize that compelling technology alone is not going to be enough to force change in the marketplace.

"Changing consumer habits, and the way they pay for things, it's not a trivial matter," says Drew Hyatt, senior vice president of mobile applications for Irvine, Calif.-based Kofax, which has developed a way to store gift card balances on consumers' mobile phones.

Hyatt was one of several conference attendees who mentioned Starbucks as the poster child for success in mobile payments. He says the difference between Starbucks and many other companies that have failed in mobile payments is that coffee drinkers stop by every day.

"To change the way somebody pays for things, you have to give them access to a new payment mechanism where they're doing three to five transactions a week," Hyatt says.