If you read some of the reviews, they will say what your saying sometimes and others say it's easy to use, but it does now want to go straight, and is hard to work with. The brown tubing they are referring to is irrigation tubing and is very thin walled. The 1/4" ID tubing we use here at our shop all the time is 120 psi but we have no problem pushing it onto a barb fitting. We use brass fittings although I wouldn't think the plastic ones would be any different.
One guy says hot water makes it real easy to push on. Try leaving it in the water a little longer. Like a minute maybe. That should soften it up.
Keep in mind that this tubing can come in many different PSI ratings starting at around 60 psi and going up over 200.