I would'nt want to be lifting those slabs
Thats why I have a skidsteer
In the pic it looks like they are sawing uphill 
That slab weights ca 1488 lb (675 kg).
This is Congo and where can I get a skid steer there? Its cheaper to pay a dozen workers than buying a skid steer.
The log on the picture is the last of three logs in a row. At that time we didn't have a mechanic jack to roll the log

Its what I call reality in the deep jungle of Congo.
We had to travel to Uganda buying a couple of 5 tons mechanic jacks. That's over 1000 miles one way.