Student or Learner
In English polls there is a question:
There ____ tons of evidence to support this view
And there is a comment, that there should be singular (is), like in lots (there is lots of sugar).
I thought a ton was countable. It is a weight unit, isn't it?
Yep, in metric it's 1000kg.. but people often say things like "I've got tons of stuff to do today", where it's interchangeable for "lots".
In your example, you can't have a measurable weight of evidence, so we know it's being used in the latter way, not countable.