I wonder how some people in here get on in life with any level of happiness, every time something bad happens, simply except it, every time a boss, or teacher, or anyone treats you like ****, accept it?
Deadlines are normally closer to guidelines than finite, there are some very strict ones, final ones usually are close but you'll usually find even the final assignment in a year actually can be extended but usually for more serious reasons than non final assignments. This is because there has to be a stop point for the year basically, other ones, what reason is there for a tutor to not want you to do your best. Everyone has bad weeks in life, should everyone fail a course because their bad week coincides with a deadline while someone elses bad week in the year is in summer.
Get a grip, anyway good you got it finished op. I've by and large had understanding tutors this year, and being the OU they are generally a bit more understanding by default compared to a standard uni.
A tutor with a "standard" student will usually allow an extension then maybe ask a few more questions and see if they can help find a solution if a second extension is require, and maybe get a lot more formal for another extension. if the tutor knows of any issues before hand and maybe expects an extension, well, a tutor knowing of any issues early is generally better as they'll know you're not pulling a fast one at the last second.
Ultimately tutors want to allow everyone some leeway, while also helping students get better at hitting deadlines, so if you're missing a lot they should talk with you about how to better hit targets, not screw you for missing them.
Either way, some teachers/tutors/professors are just bad, some are brilliant, some are mean because they can be, some are mean because you need it, there is no one right way to teach. A tutor who will give a student who is known to have started basically 2 months after everyone else, shorter deadlines and more grief is just being a pratt.