"Mr. President, you have to....because it's traditional."

I would have thought there were sound logistical and security reasons for that. Presidents have certainly gone out and about in other ways (Clinton used to go jogging) but any travel not using the above vehicles will increase the level of security arrangements required.

Yes, that’s not something that’s done because it’s traditional, but because of security concerns. The President isn’t going to fly commercial or take an Uber.