"It allows for instances where the normal constraints don't apply."
Naturally, some context would be helpful.
Your example doesn't help; it's not logical.
But look, do you know what an exception is? You should look up a dictionary or three for this.
We can take as an example a system that allows for exceptions. Taxation in your example is the 'it' in "It provides for exceptions."
So, we have this tax - an income tax, say. The tax system is this: you must pay 30% tax on all income you make, if you earn over $10,000 a year. This taxation system provides for one exception. Can you spot it?
(Barb)Please put your question in the body of your post, not as the title.
It means that the rule does not apply to everyone. It allows exceptions. In this case, provides for is an idomatic expression for allows.
In your example, truck drivers do not have to pay the tax.
Just click the Thank button, please.How [STRIKE]to [/STRIKE]do I give thanks for a post[STRIKE]![/STRIKE]?[STRIKE]?[/STRIKE]