Tubular locks are extremely simple to pick. The only reason they're used is because they're cheap and used to protect cheap stuff, like food in vending machines
Some tubular locks are simple to pick and yes a modified bic pen is the poor man's pick but it's certainly not all of them that can be done that easily.
Anyone can pick the lock in seconds if they take the time to learn.
My dad owned a few vending machines when I was a kid. Since they were used, he had to replace the locks on all of them and taught us how to pick them. It's relatively easy to do so. I think he only ever ended up drilling out one of the cylinders while he was able to pick the rest.
A Bic pen won't work that well, but a $50 pick will.