An ongoing investigation by ProPublica and BuzzFeed News found Amazon delivery drivers have been involved in more than 60 crashes causing injuries or death since June 2015. That joint investigation found that drivers reported feeling tremendous pressure to meet deadlines and that Amazon often avoids liability for accidents.

Amazon estimates it will have about 50,000 delivery vehicles on the road during the holidays.

One family who lost their daughter in a crash with a delivery driver said no life is worth a package. Chad and Ellen Kennedy's 10-month-old daughter, Gabrielle, was killed in January when a delivery driver hit Ellen's car.

"My eyes went back to the rear-view mirror and that was when I just saw the headlights," Ellen said.

According to the ProPublica-BuzzFeed News investigation from September, the driver was hauling packages for an Amazon subcontractor. Those contractors are often liable if there's an accident, not Amazon.

"Really serious things that go wrong with these deliveries, it's never Amazon's problem," ProPublica senior reporter Patricia Callahan said. "Amazon has actually sued to enforce the terms of these agreements."

Callahan said, despite avoiding liability, Amazon has a tight grip on the day-to-day. The company can even tell drivers to turn left or right on a particular route.

"Amazon knows where they are on the road, it's telling them the order in which they can deliver each package," Callahan said. "There's a dispatcher in an Amazon warehouse that can check on their progress and call them and say, 'Where are you? Why isn't it there?'"

Through work orders, Callahan found that Amazon requires 999 out of 1,000 deliveries to arrive on time. Amazon refuted that claim and said while they have expectations of their drivers, there are no quotas.

"The drivers overwhelmingly talked about the pressure that's on them," Callahan said. "Drivers talked about urinating in bottles because they don't have time to stop and use a bathroom."

Callahan said the driver who hit Ellen Kennedy said he was feeling pressured that day because he was running behind, but the contractor who employed him refuted that. In an exclusive interview with CBS News, Dave Clark, senior vice president of worldwide operations at Amazon said safety comes first.

"We're focused on background and driving check to make sure that the people we put in the vehicle come from a place of good driving record, a good safety record" Clark told CBS News' Mola Lenghi. "And then we train them before they ever hit the road."

Clark highlighted the technology they use to monitor drivers' actions as an added safety net. But sometimes, Clark said, accidents happen.

"When you drive 800 million miles there will be accidents, unfortunately," Clark said. "Our focus is about how you reduce those. How do we get our routing to ensure that we're putting people in the conditions to where they're not having to back out of neighborhoods, they're not having to make as many left-hand turns, they're really not having to rush through the course the day."

As for the Kennedys, the father told us they settled in a suit with the contractor, but they insist no dollar amount could quell their grief.

"There's no price on my daughter's life," Chad said. "But if I could save another family from this tragedy, that's the reason why I want to talk to people."

Amazon previously declined to answer questions about demands it placed on drivers. It also said the ProPublica-BuzzFeed News investigation did not accurately represent the company's commitment to safety.

In response to CBS News, Amazon extended condolences to the Kennedys and said if a driver is struggling to complete shipments, it deploys resources to help.