Canadian Broadband → How is this difference in available DSL service even possible?

I and my parents live within 2 min walking distance from each other.
My subdivision was closed 2 years earlier than theirs, i.e. 9 years ago versus 7.
My house is about 300 yards closer to Bell concentrator that entire area is on.
But!
I can only get 7 mbit at my house, while the parents can get up to 50 on DSL.

How's that possible?

Besides that, my connection experiences growing packet loss every about 3-4 years (this is the 3d one so far) and previous instances were fixed by replacing transmitters in the demarcation box or concentrator. The parents' connection never had any crap like that.

The lines may go a different route. I know in the case of my street, they loop around the street in a way that puts me near the end even though I am near the entrance to our street.

It could also just bee the quality of the lines. There may be something causing poor signal on yours.

You may be on the CO, they could be on a remote.

Like donoreo said, it all depends where the wires go...

Sometimes one side of a street has completely different level of services available than the other...

LOL. Sucks to be Bell then, I guess.
Is this only possible in Canaduh or worldwide?

It is the nature of the technology.

Yep one of the reasons why I switched to Cable. Maxed out line, pretty much SOL.

I would agree, if the goal was to specifically create situations where different addresses had substantially different levels of service. Then Bell could create sophisticated routing map to achieve drastically different cable lengths.
But in a real world every length of cable has price, and substantial price mind you, thus my people living 300 yards further from the concentrator should not have 10x times better signal than me.
That would essentially mean, that they connected newer houses in the same subdivision with a straight cable, but created a convoluted web of wires in the older one.
Extremely hard to believe scenario I must tell you.
Especially considering that 50 mbit service yields 2x the revenue.
They just started laying fiberoptics in our area and both subdivisions will be entirely on fiber, but it's not there yet, so different technology is not a factor yet.

Hell, you can even live next door or across the street and have that same thing happen - it's just the way it is

You and your parents are both fed from different distribution terminals and there area was upgraded first. Your parents area is connected to a fiber fed remote that is at the distribution terminal whereas you are fed from a Central Office (CO) and due to your distance from the CO you can't get any higher than 7Mbps.A number of factors could be causing packet loss; bad ethernet cable between the modem, router or computer, interference if it's wireless, bad modem, bad router, issues on the computer, cable issues, bad DSL port, bad wiring inside your house. The only to find out the problem for sure is to schedule a technician visit.If all the cables in your area are buried than you will not be getting Fiber to the Home (FTTH), your area will be getting Fiber to the Node (FTTN). Bell will be bringing the fiber to the distribution terminals that feeds your neighbourhood and than it will continue along the existing copper cable to your house.

It's always possible that their qualification data is out of date. You can try calling Bell to see if they can confirm it, I don't know if their phone reps get any more data than what's available online though.

As far as distance, your distance down to the metre does matter. It's entirely possible that if there is something like 600 m of cabling for your parents and 900 m of cabling for you, they would qualify and you don't.
Bell has gotten better at qualification in recent years and generally won't qualify an address for higher speeds (especially 25 and up) unless it's actually obtainable, and those do require you literally being within hundreds of metres from a remote.