I bet not many people have the guts to call themselves mechanical engineers just because they know how to fix the break pump of a car, for example.
Just having a software engineering degree alone should not really make you an engineer, in this respect, any more than someone who has studied software development practices through other means.
In software engineering this is even more blurry, for example my school offered both computer science as software engineering degrees. However in practise the only difference was that the software engineering track had a mandatory module on UML.
At least here in Norway 'Engineer' is not a protected title (but Civil Engineer is), so anyone could just call themselves an engineer.
But unless you have tons of experience and can prove you know the required things then I doubt you will be getting a job as a Construction Engineer or something like that without a degree.
In IT I doubt anyone cares as long as you prove yourself capable.
In places which more rigorously enforce titles it is usually down to a professional body to set requirements, though even then these tend to not mandate a degree (though that makes the path smoother). For example the IEEE requires either an IEEE accredited degree or 6 years of proven work experience in a relevant field to achieve member status.
In the UK we have a institution for IT professionals (The British Computer Society) though as far as I can tell nobody really cares much about it.
Even met one of these once http://en.wikipedia.org/wiki/Certified_Software_Development_... he was a scarily good software engineer.
Think about online marketing practices like SEO. There is no university which is really teaching you how search engines work and you can influence them. You can only read as much as you can and learn on your own experiences.
And even if you have a degree and call yourself a software engineer, it does not imply that you are a one, does it?