Because it reduces their cost on a route they were already going to take. It's the actual sharing part of the so-called 'sharing economy'.

Because the cost of fuel in the EU is quite high, and a lot of people commute long(er) distances on a regular basis instead of flying.

It is considered an entirely acceptable system because the "cost reimbursement" will fully cover the cost of wear + tear + fuel, meaning that a drive across the country can be rendered effectively free for the driver.

Also, "without any income for the driver" isn't necessarily correct - if you have a full car you will make a tidy profit.

Edit: the cost of a blablacar trip to a passenger would be on the order of 13-16 euros for an hour's drive. Comparable or cheaper than a train, with more flexibility.

Because BlaBlaCar is NOT a taxi service. They can't operate in Europe as a Taxi service, as it will be illegal to have a Taxi service without the proper permissions, paying proper taxes, etc. So they are doing REAL car sharing. Some one helps you to pay for the cost of the trip, and that's it. It's the old car pooling but more teachy.

Others have talked about fuel costs, but some BlaBla drivers I've met simply wanted company in longer solitary trips.

At least here in Finland, you are only allowed to share the expenses and not profit from it (unless you're a registered taxi driver and have the permit). There is a small incentive for the driver if he/she is heading the same direction anyway but otherwise you're right, it doesn't make any sense for the driver. So it's quite different from Uber in that sense.

because if you make a profit you need a professional insurance and or a taxi license. blablacar is a carpool service where the driver is not professional. You use it to recoup fuel costs and tolls.

Other justifications are: having company, decreasing your carbon footprint.

> Then why would any driver want to provide services via the app?

The incentive of the driver is sharing the cost of the gasoline/roads with the rider. Cost of gasoline in EU is higher than in US.

Because if they profit they are either uninsured, or need to sort out extra cover.

Wouldn't being uninsured for liability be equally bad whether the driver makes a profit or not? If you injure someone and are at fault or get sued, that's a major civil liability, regardless of whether the person you injured was paying you or not.

As long as you don't make a profit the usual (and legally mandated) liability insurance covers all passengers.

I see, right, because personal drivers' insurance will often have exclusions for business use.