When it comes to tipping, you’d think that the generation most often stuck in service jobs right out of college would get it. But a new study from creditcards.com shows that this cohort is actually the worst at leaving 15-20%.

Why would a generation known for promoting social good do this to the service industry?

Three reasons:

Technology, The Root Of All Evil

Many millennials make most of their purchases online where tipping is not even an option. Even for everyday purchases, millennials are the most active users of paying platforms like Paypal and Venmo. Some platforms don’t lend themselves to tipping either.

Coupled with the fact that some millennials may not be accustomed to eating out often as older generations, some of them simply aren’t used to leaving a tip.

It’s The Principal Of It

Some millennials refuse to leave a tip because they don’t agree with the almost obligatory practice. Many have expressed that they feel service workers, whether in restaurants or elsewhere, should be paid a living wage. It shouldn’t be up to the customer to pay for a service and help cover the business owner’s payroll expenses.

Millennials also travel more than other generations. They have been first-hand observers of the tipping system in other countries, where tips are only left if the server did something exceptional, and they tip with that method in America too.

Millennials Really Are Broke

Lastly, many millennials can’t afford home ownership, so they pay high rent. In some metropolitan areas, millennials can’t afford cars, so every trip they take is an expense. Many millennials are also drowning in student loans, paid less than older generations, and are given poor benefits at work. Life is expensive, and some millennials flat out can’t afford to leave a tip.

It goes without saying that term “millennials”┬árepresents an entire generation. All of them aren’t poor. All of them aren’t bad tippers. Still, this study is yet another reminder of the unique challenges facing this generation.