Why is salmon packed in cans with non parallel sides?

[sharkeeper]

The cans remind me of a bucket or wastebasket. They are taller as well.

Example

 

[Anonemous]

hmmm i have a can of salmon that has parallel sides...

 

[radioouman]

uhhhh, so it will come out?

 

[sharkeeper]

hmmm i have a can of salmon that has parallel sides...

That's the cheap stuff!

uhhhh, so it will come out?

So why just salmon then?