A 1985 article, "Bound for America," provides an overview of British Government policy after the passage of the Transportation Act of 1718. Most of the estimated 50,000 individuals transported during this period were from England, with smaller numbers from Scotland and Ireland. In most cases transportation was seen as a merciful punishment for capital crimes. And in lesser cases, judge and juries tried to avoid transportation by sentencing people to whippings or other punishments. And while today, we might prefer exile to a public whipping, in the eighteenth century a great many people did not survive their first year in the Americas.
Using available records, Ekirch profiles those banished to the British colonies between 1718 and 1775. His analysis finds that those banished tended to be young men without any particular skills who were drawn to criminal activity because they could not find steady employment. This contrasted with those who bound themselves as indentured servants as they tended to be the highly skilled. Individuals with skills were in great demand in the colonies. The Americans were, understandably, not keen on having British criminals dumped on their on their shores, but they were unskilled and that was even worse. But as Ekirch points out, transportation existed to serve the needs of the British State, not the American economy.
Ekirch, A. Roger. “Bound for America: A Profile of British Convicts Transported to the Colonies, 1718-1775.” William and Mary Quarterly, 3rd Series., Vol. 42, No. 2 (Apr. 1985), 184-200. The Stable JSOTR URL is here; check to see if your local public library has a subscription to JSTOR.