IE handles input fields completely differently than Chrome and FF, why?

Question

Browsers

Today, while testing a small addition of site functionality, I came across the fact that IE10 handles input fields differently than Chrome and FF (Mozilla is constantly updated, Chrome is also fresh).
For example, in IE, when you try to enter something like blabla123 in the number field, an alert is displayed with the text "Incorrect value" and the value in the field does not change.
But in FF and Chrome, with the same actions, the new value is quite calmly accepted, but replaced by 0.
TL says that this is expected behavior, because it's just that everything is cast to the desired type (int).
Well, why is it not shown in IE?
Another example. In IE, if you open a form for entering a value, the field already contains the previously entered value, and if you do not change it, click Accept, then the value will remain the same. In Chrome and FF, when opening the form, the input field is empty and if you click Accept, the previously set value will be reset to zero.
Ie completely different behavior.
I'm a tester (only a few months experience) and with this whole situation I'm in a quandary: what is the expected behavior to write in tests? After all, the forms are worked out in completely different ways.
Tomorrow I'm waiting for a response from TL about this, but now I'm interested in opinions. Why is this happening and is there anything I can do about it.
I ask you not to kick for such a generalized question, without code examples, etc. The goal is not worth understanding at all costs, just curious in general terms to find out what reasons there may be for such behavior.
Bootstrap site, if that matters.

Answer 1

Browser engines are different, so there is no single specification for the functionality of any elements, who did as he could :)