The assessed value itself comes from mass appraisal, the City valuing thousands of properties from recorded attributes and a fixed base date rather than visiting each one individually, which is a practical way to distribute a citywide tax burden but not a precise way to price one specific Lawson Heights house.
Because Lawson Heights includes a range of housing ages and sizes, two neighbouring homes can carry noticeably different bills even at similar market value, if one was last reassessed at a different point in the cycle than the other or if the City's recorded attributes, square footage, basement development, a garage, differ from reality.
Checking your own notice against the physical details on file is the fastest way to confirm the calculation is actually right for your house. Get your hand-reviewed valuation from Joel Dyck.