I don't totally agree with that, but I think Tech and those other two have one big difference.
Miami and LA can bandwagon on their teams. USC can generate buzz. Miami, could get good enough to sell out that NFL stadium.
Tech is a nerd school with hardly a neighborhood in the metro that has more Tech fans than UGA fans. Even if Miami nominally doesn't care about the 'Canes (probably), that interest far outweighs the paltry following of Tech. (Plus Tech's academics make it a challenge on a number of levels)
USC can generate buzz when they win. It's a historical blue blood. One of the founding member/building blocks of CFB. And during it's most recent glory years of the Carroll era, it was the only football in town as the NFL had abandoned LA for decades. USC also has Hollywood behind it. Lot of very famous people are like diehard for USC Trojans football. Can't compare that to Miami who has what- some random ass one hit wonder rapper from Miami that nobody really even knows like Luther Campbell.
Miami is not that. At all. Not even close. They are not a blue blood. They are not a founding/building block member of the sport. They are more or less an anomaly that hit it huge in the mid 1980s and stayed on a huge winning track for 7-8 years until about '94 then fell off a cliff, then rebounded in the early 2000s in a huge way for about a 4 year run under Butch Davis/Larry Coker and then fell off a cliff again and has been mediocre or even very bad every year for the last 17 years.
And the Miami Dolphins are about the only football people in South Florida really care about at all. Miami can't bandwagon on their teams if nobody gives a shit about them. Miami couldn't even sell out that dump of a garbage stadium in Little Havanna that the Dolphins left them when they moved into Joe Robbie (now Hard Rock) when they were really good. Shows you how much the city gov't cares about Miami Canes football- they wouldn't let the Canes keep the dump in Little Havanna- the city leveled it to the ground to build the MLB team a stadium- despite U of Miami fighting tooth and nail with the city to let them keep it. Miami Hurricanes can't even compete in Miami with the Marlins for fans/support. They are a 3rd class citizen, red-headed step child in their own backyard. Miami nominally doesn't care about the 'Canes (probably) - they literally don't give a shit about the Canes. At all.
I've lived in South Florida for over 20 years. I've been to games at the old Orange Bowl when Miami was a dominant program. They had trouble selling it out then, and it was much closer to their campus. They will never in a million years sell out the NFL stadium that is further away. You'll find more fans of other CFB teams in Miami than you will fans of the Canes. Florida, FSU, LSU, Alabama, Notre Dame, Ohio State, Michigan, Penn State- you name it- have tons of fans in South Florida- and they out-weight the Canes fans.
Miami is a small private school in a rich suburb where homes routinely sell for $5, $10, $15, $20, $30, even upwards of $50 million. An old piece of crap 1,200 sq ft home on barely over a tenth acre on a zero lot line in Coral Gables will cost you $700k minimum. It's not some college town that lives and breathes football. It's most very rich people, that really don't give a shit about that sport. They like tennis, golf, polo- you know- rich people sports.