Can the word 'trafficking' mean 'freight transportation' without conveying the meaning of being illegal ? (Especially in the following sentence)

You should avoid the use of "to traffic" in reference to legal commerce.

The use of "to traffic" in reference to legal trading has declined, and is now all but obsolete or regional:

The OED explains:

Traffic (v.) 1.a. intransitive. To engage in trade or commerce, esp. between one country, region, or community and another; to buy and sell, or barter, goods or commodities; to trade. Also occasionally: to travel for the purpose of trade.

Now rare and chiefly historical.

[...] With the increasing dominance in the 20th cent. of the senses relating to illegal or illicit trade [...], this sense and others relating to lawful or acceptable trade generally declined [...]. However, this sense is still current in the Caribbean with reference to legitimate trading between the Caribbean Islands and neighbouring territories in agricultural produce and household goods (see quot. 1990 and cf. trafficker n. 1a).

1773 J. Hawkesworth Acct. Voy. Southern Hemisphere II. i. ix. 93 They trafficked with us for cocoa-nuts and other fruit.

1990 M. Lagro & D. Plotkin Agric. Traders of St. Vincent & Grenadines ii. 11 The number of traders appears to have declined as older traders who had been trafficking for many years have dropped out.

2b. intransitive. With in. To trade in or procure human beings for the purpose of slavery or exploitation; (in later use esp.) to relocate people forcibly or illegally from one country or region to another, typically for coercion into prostitution, forced labour, or other forms of exploitation. Later also transitive with person as object [...].Originally perhaps simply a contextual use of sense 2a, but from the early 20th cent. emerging as a distinct sense.

1817 Trewman's Exeter Flying-post 6 Mar. It is made a felony, subject to 14 years' transportation, for any person to be trafficking in Slaves.

2016 J. A. Reid et al. in J. A. Reid Human Trafficking v. 79 The victim was trafficked by her father and exploited by other men when she was a preadolescent.

c. transitive. To trade or deal illegally or illicitly in (something); (now esp.) to transport (officially controlled or stolen goods or substances) from one country or region to another in the course of illegal trade. Also (and earliest) intransitive, chiefly with in.

Apparently originally used with reference to illicit trading within prisons, and gaining currency in the second half of the 20th cent.**

1896 Islander (Friday Harbor, Washington) 21 May He has made open charges to the board of directors, that employes of the prison are trafficking in the drug.

2013 Small Arms Surv.: Everyday Dangers iv. 93 Western Balkans, the Russian Federation, and Eastern Europe are key sources of firearms trafficked into the EU.

I mostly agree with the answer provided by Greybeard; however, I believe the OED either is incorrect or misleading in the following sense (regarding the definition at 1.a.):

Traffick implies the transportation of a substance from one place to another (viz.: a person can traffick in soil, but cannot traffick in land).

This remains true even when relocated soil is used to "create land," as it is not actually land (which is defined by geospatial position) that is being created, but a firmament is being constructed where the "land" previously consisted in either air or water covering an underlying body of (dirt, rock, sand, etc).

Thus one can traffick in portable buildings (commonly: "a building intended to be transported via road") but — excepting sci-fi or supernatural ability — not in skyscrapers or stadiums.

These observations (supra) are consistent with the examples given in the citation.

Reclaiming words is a vital part of the author's role in protecting the transmission of intelligence across generations: obsessive expansion in some areas, contraction in other areas, and reimagination of words and their meanings ultimately renders written works unintelligible.

This is not to argue for a rigid list of words and corresponding definitions; however, it is to argue both for the preservation of words (even those not "politically correct") and historic meanings, and for the careful and non-frivolous modification of our language.