because both parties are actually on the same side - the side of the elites. the elites alternate their support for either side depending on what's currently needed to manage the populace. forget the sudden gearshift of the dnc in dropping support for biden in favour of harris, we witnessed the exact thing happen with trump where the establishment castigated him for 8 years, tried to impeach him, try to arrest him, then suddenly do a 180 in both mainstream media and financial aipac support when us-israel tensions in gaza got heated between biden and netanyahu, and trump openly pledged unilateral support for israel. the republicans are in power now because the elites went overboard in steering the democrats into identity politics (which was originally introduced along with blm to undermine the class war/movement of occupy wallstreet). the public became disillusioned with identity politics and its foray into mass censorship and cancel culture, which led to the current republican swing. this in turn has the populace turn their attentions back on to the class war (especially with the recent healthcare related shooting), which in the future may require the elites to 'elect' a democratic regime/administration to placate them once more. basically there's no democracy in the us, it's just the illusion of choice while a single entity puppeteers both sides as a means to stay in control.
Canada