This seems a peculiarly American way to go about things ... specifically, it's not actually about protection or transport at all: it's about signalling imperial primacy through conspicuous misuse of resources.

I live in Edinburgh, capital of Scotland, about a mile away from a royal palace that is sometimes occupied by actual royals. (Typically Princess Anne; sometimes Charles, William, or the Queen when she's in town to open a session of the Scottish Parliament.)

And as I live on a main road they sometimes drive past my front door.

A royal motorcade scaled for the heir to the throne and his wife, or the queen's sister, or a similar level of VIP, consists of: two SUVs (typically Range Rovers) and 2-4 motorcycles. One SUV for the VIPs (presumably armoured), one for additional security/backup, and the bikes leap-frog the SUVs to stop traffic at intersections so the SUVs don't need to slow down.

The SUVs are notable for not having number plates (that's normally illegal in the UK). And for special appearances the VIP carrier is sometimes replaced with a classic limousine -- I've seen Daimlers and Rolls-Royces used (older, pre-BMW-ownership ones).

The queen isn't a common visitor these days (she's 95, doesn't travel much during the pandemic) but used to rate something not much larger: add another couple of Range Rovers to the convoy and that's about it.

What they don't do is shut down an entire city and have military helicopters and transports flying around the place, signaling what's going on. The emphasis seems to be on being discreet and agile, and able to avoid any possible threats notified by intelligence. If you've got a convoy involving a hundred people you can't simply pick another route.

Now, obviously the rules are a bit different for the leader of the global imperial hegemon: projecting an image of invulnerability and overwhelming might goes with the territory. And a formal parade like a Presidential Inauguration or a state visit calls for laying on the pomp, ceremony, and escort size (a UK example might be the Trooping of the Colours, or the state opening of Parliament and the monarch's speech).

But if the objective of the presidential motorcade is to safely deliver POTUS to a speaking engagement then safely extract him afterwards, with elbow-room for close protection duty, then 95% of this motorcade arrangement is a very expensive waste of people and equipment: it's signalling that the subject of the motorcade is important, not actually accomplishing anything tangible.