SVG icons not being scaled correctly

Thanks I accept the Pictures are rectangular but why are they not automatically sized from the SVG’s viewbox? It does seem that the picture inherits the width and height of the SVG if those attributes are in the svg element, but you don’t look at the viewbox attribute. Why?

See the example small icon below that does not have width and height specified in the file but does have a viewbox of “0 0 75 75”.

image

I am using Chrome, which I note has a problem with the example

And finally here is the outcome if I specify height/width in the SVG and in the Picture which is not right either.

image