“In a rideshare, these people have no health care, no vacation or sick days. They’re not getting a whole lot of money, so I have to be savvy enough to understand that,” says Smith, the president of Mannersmith Etiquette Consulting. “If it’s rush hour, I’m going to tip more. I’m tipping in the 20% range.”

The beauty of these apps is that there’s no face-to-face hand-off of the tip, Coggins explains. And you can do it after the fact, as well. “I think people are dying not to have to be in these situations. It’s so fraught, because you’re having to put a value on someone’s work.”

Airbnb vs. Hotel
When staying at a traditional hotel, guests should leave a cash tip each day, says Elaine Swann, founder of the Swann School of Protocol in California. She suggests from $5 to $10 a day. But when staying at an Airbnb, Vrbo, or other home rental, she typically eschews a tip.

“Most of the fees are built into the cost of it, so you don’t have to leave a tip,” she says. “Then, that’s up to the discretion of the owner to pass along to the cleaning service, or pocket it for themselves. I would not say it’s required.”

Similarly, Maryanne Parker, founder of San Diego-based Manor of Manners, stresses the importance of leaving a cash tip at a hotel each day because the cleaning staff may change during the length of your stay. “You should write a note and let them know that this is a tip,” she says. “You need to very directly explain.” Even a simple ‘Thank You’ can do it, lest housekeeping staff leave the money so they won’t accused of stealing.

For home shares, cash is unnecessary, but she suggests leaving a thank-you note for the hosts, especially if they were very responsive and went out of their way to improve your trip.

That Intrusive iPad 
Many coffee shops, food trucks, and quick-service eateries now use iPad point-of-sale systems that are swiveled to customers, prompting them to choose options after swiping their cards—“no tip” or options between 10% and 20%.

Paul Bagdan, professor at the College of Hospitality Management at Johnson & Wales University in Rhode Island, calls this “guilt tipping.”

“People tip more when prompted to, or when they have to decline, especially when the person is right in front of you,” he says.

Smith explains that it’s not necessary to leave a tip if the employee is simply handing you an item from behind the counter. She might leave a dollar or two in a nearby tip jar if her order is unusually complicated or if she visits the shop often.