Here is a suggestion how they could use "droga" three times in one sentence:
Moja droga, ta droga jest za droga! (My dear, this road is too expensive!)
Is this a common saying because of the rhyme, or just a cute phrase that they made up for this course?
It is not a common saying ( I think)
but it is not a rare thing to complain about cost of building roads in Poland and/or cost of paid roads in Poland, and the pun that is common in that discussion.
I (?mis)understood "ta droga jest za droga" in the sense of "this road is too expensive (to live in)" - a common complaint about the cost of housing in some parts of the UK.
A street is a road in a built environment. So it is surrounded by buildings. A road doesn't have to.
I wonder if they created a sentence with the two meanings of "mamy" - we have, and mom's (of mom, belonging to mom)...
Z nami my mamy mojej mamy wybrane bramy. With us we have my mum's chosen gates.
In the States the words "road" and "street" are often used interchangeably (in fact, I doubt that most people know what the official definition is). Is this not the case in Polish? I.e., is "ulica" strictly for paved roadways in an urban environment?