I have turned on strict URL’s and am able to generate the 404 for pages that don’t exist at segment_1 however at segment_2 it will not trigger, it just stays on the index of that template group i.e.
mysite.com/about/dfdfdf - just stays on about page but:
mysite.com/asfsdfd - will trigger the 404.
I have index.php removed via the htaccess.
I find it increaingly frustrating to get 404 templates working correctly in EE, WordPress handles them perfectly out the box which is great for SEO.
I have read on conditionals for segments to trigger but this method does not suit our template structure because we are using some templates to display a list of entries plus the single entry.