First, why are you focusing on the word passenger anyway? Neither the terms vehicle nor motor vehicle in § 55-1-103 use that word. Thus, that word doesn't help you in what motor vehicle means in that section. Use the words of the statute and don't try to add in words that are not there.
Even if it was in the statute, it would not help you as the definition of the term passenger today does not mean what you say it does. The current definition of motor vehicle was put in § 55-1-103 in 2019. So a court would look at the meaning of the term in 2019 to determine what the legislature meant. In doing so, the ordinary English language definition applies unless it is clear the legislature meant something else. From a pretty recent Tennessee appellate court decision:
Our goal in statutory interpretation is to “ascertain and effectuate the legislature's intent.” Kite v. Kite, 22 S.W.3d 803, 805 (Tenn. 1997). When a statute's language is unambiguous, we derive legislative intent from the statute's plain language. Carson Creek Vacation Resorts, Inc. v. Dep't of Revenue, 865 S.W.2d 1, 2 (Tenn. 1993). The words used in the statute should be given their natural, ordinary meaning “in the context in which they appear in the statute and in light of the statute's general purpose.”
In re Estate of Starkey, 556 S.W.3d 811, 815 (Tenn. Ct. App. 2018). And the Tennessee Supreme Court in 2015 said the same thing:
The role of this Court in statutory interpretation is to assign a statute the full effect of the legislative intent without restricting or expanding the intended scope of the statute. See Lee Med., Inc. v. Beecher, 312 S.W.3d 515, 527 (Tenn.2010); Larsen–Ball v. Ball, 301 S.W.3d 228, 232 (Tenn.2010). In doing so, we first must look to the text of the statute and give the words of the statute “their natural and ordinary meaning in the context in which they appear and in light of the statute's general purpose.” Mills v. Fulmarque, Inc., 360 S.W.3d 362, 368 (Tenn.2012) (citing Lee Med., Inc., 312 S.W.3d at 526; Hayes v. Gibson Cnty., 288 S.W.3d 334, 337 (Tenn.2009); Waldschmidt v. Reassure Am. Life Ins. Co., 271 S.W.3d 173, 176 (Tenn.2008)). Therefore, when the language of a statute is clear and unambiguous, we need look no further than the plain and ordinary meaning of the statutory language. See Mills, 360 S.W.3d at 368. That is, “we presume that every word in the statute has meaning and purpose and should be given full effect if the obvious intent of the General Assembly is not violated by so doing.” Larsen–Ball, 301 S.W.3d at 232.
Davis ex rel. Davis v. Ibach, 465 S.W.3d 570, 573 (Tenn. 2015)(bolding added).
So that's how the Tennessee courts will go about defining the terms used. Unless a contrary intent is reflected in the statute, the plain and ordinary meaning of the words is what they will use.
Where the legislature uses a term that is a specialized legal term, what lawyers call a term of art, the courts may presume that what the legislature intended. And Black's Law Dictionary is certainly the most common resource courts use for those kinds of legal terms.
But he problem for you is the word passenger is not a word with a specific legal meaning. Not anymore. Look at the current editions of Black's, the 10th and 11th Editions (the 11th is brand new). Neither edition has a definition for it. Indeed, there hasn't been a definition for it in Black's since at least the 7th edition, which goes back over 20 years.
Since you like relying on Scalia's explanations of things, I'll point out that the 7th Edition was the first edition edited by Bryan Garner, a well respected authority on legal writing and who was Scalia's co-author on several books. He has done every edition since. He significantly updated and modernized Black's, getting rid of a number of words that no longer were used in the law.
Times change and definitions of words change along with them. The court isn't going to use an ancient law dictionary from 100 years ago to define terms for a definition enacted in 2019. It will use modern dictionaries.
And since Black's no longer defines the term, the ordinary meaning found in Webster's is what courts tend to go to. And Webster's defines it as:
2 : a traveler in a public or private conveyance
The term is thus not limited to someone who has paid for transport.
As I said to you before, one of mistakes you are making (which is what those web sites that push the same arguments you are using) is that they use out-of-date cases, statutes, and yes, out of date dictionaries. Old materials that have been surpassed by new ones are not helpful to you since newer cases, statutes, etc that apply as they supercede the old ones. Don't rely on a dictionary from 1910 to define a word today.