The professional junk hauler will assist you with throwing out your things by handling the physical, exhausting labor of carrying your pile of junk out of the garage. Then the items are loaded onto the van and removed to their staging area and systematically rendered into categories of recyclable material. Sometimes there are things that can be refurbished and used by another so the landfill is avoided.
You could argue that refurbishing and recycling their own junk would be a more affordable way to get rid of junk, but in 98% of instances people pick the easiest way out and just throw their junk in the usual trash. That is usually going to end up in the dump where it becomes a problem.
To get rid of junk responsibly it is best to include somebody with experience, who will make sure that the most junk possible will be recycled or reused in some aspect. Normally home owners don't have the knowledge or experience required to keep their discarded items out of the dumps.
An additional factor in getting rid of junk is that it can be heavy to move and bringing in professionals will eliminate the possibility that they won't get injured. This is the driving reason that the junk hauling market is growing so fast. The Baby Boomer generation is deciding for their own safety and to preserve the environment.
You can also argue that the junk hauler is raking in even more money with recycling. That is certainly true but you must think about the costs involved. Insurance, a truck, landfill fees, employees to sort through the stuff and gasoline. There is always a removal charge to get rid of junk. If you do it alone you have various risks to overcome and then you need the specialized knowledge to understand how to profit from the recycling of your junk.
In my experience opinion it would be far more beneficial to the planet to use a professional junk hauler. Setting aside the risk components you won't be wasting money by hiring people to haul off your junk. After the aggravation of getting your junk to the landfill you will then be charged a price for the amount of junk you have. Finding help to assist in your project, understanding what can be sold as recyclable material, risk that someone will get hurt, and even the gas are all problems that you will need to overcome. The alternative is to hire a junk hauler, when they arrive point out what is being dicarded and you're done in less than an hour.