If you ever thought that mobile payments, mobile ordering, and other such mobile technologies were having some kind of impact on the restaurant business, but you weren’t sure just what kind of impact, take a moment to congratulate yourself on such highly-toned instincts.

Then, take a look at the output of a recent study from American Express to fill in some of the blanks in this rapidly-changing frontier of restaurants.

The American Express study found that mobile apps and websites play an increasingly pronounced role in ordering patterns throughout all generations, but not surprisingly, most pronounced for millennials. Millennials reported using a mobile app or website to order food at least once in the last month in 62 percent of cases. Baby boomers, however, did likewise in 28 percent of cases.

Most want to tip, though this varies too. Millennials are actually least likely to tip, instead favoring a service charge added on to the bill. Roughly 30 percent of restaurants have actually responded to this by actively eliminating tipping, or considering it if competitors go ahead first.

Most, interestingly, want some kind of wait staff involved, but fully one in four want to place orders through digital platforms. Given that only seven percent of restaurants offer such technology, there’s a clear lag there between desire and delivery, but it’s a point that’s set to grow as 26 percent have at least some plan or interest in bringing the technology forward.

Those who want to bring in the millennial market will have to make substantial upgrades to available technology, as well as fundamentally reshape many attitudes about food waste, social media and a variety of other topics.

Those who don’t make those adjustments, meanwhile, will have a substantial market to cater to instead…but a market with a shelf life. There’s certainly room in offering food to boomers and Generation X…but these markets are aging, and often eating less in general.

Businesses therefore may have a difficult balancing act afoot, and could have a tough time going forward of offering what the millennials want alongside what everyone else wants. Mobile payments and mobile ordering systems, however, have a fairly universal appeal and may be able to deliver value universally.