I agree these are over simplistic labels to use, as is the idea that political views can all be neatly distributed on a 1 dimensional chart, but still when  a group of people all acting in a particular way all seem to also espouse the same beliefs as another group of people it is useful to recognize that with labels.
People who identify as being "on the left" seem to mostly agree with a set of ideas that are different than those held by people who identify as being "on the right."
And of course it depends on your domain of discourse. Virtually every US president for the last 50 years would be considered to be to the right of virtually all Canadian PMs. Compared to the US Canada is heavily socialist, compared to Sweden Canada is hardly socialist at all and compared to Somalia... well you can't really make broad generalizations at all in any meaningful way.