Uber and Lyft provide flexible work for millions of drivers with a very low barrier to entry.

But despite the benefits, many say there are things they wish they had known before starting to drive.

Everything from insurance, to taxes, to vehicle wear and tear make driving for the companies more complicated than you might think.

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More than two million people have signed up to drive for Uber and Lyft around the world.

That ride-hailing explosion has unlocked new travel (and dining) options for billions of people, while providing flexible work and additional income for the independent contractors who power the apps' services.

But for some drivers, the job ended up being different than what they expected. From the loneliness that comes from having no boss or coworkers, to unforeseen wear and tear on their vehicles, drivers have plenty of advice for those who might also be thinking about firing up their phones and hitting the road.

Here's what more than 20 drivers told Business Insider they wish they would have realized sooner: