In the early days, printing was an especially expensive business. A large investment in the printing equipment itself, the cost of paper, and labor constituted a significant investment that could only be recouped much later on — if at all!
Printing privileges (the first in Europe issued in Venice to the printing firm of the Da Spira brothers in 1469) were intended to restrict the production of competing editions. In this respect, they were a type of monopoly privilege. Privileges were also awarded to protect a specific printing technology.
“In an era before legal copyright, Aldus was quick to protect both his newly designed italic type and the editions in which those types appeared from the pirates and counterfeiters the best way he could. In 1502 he was granted ‘privileges’ (the exclusive right to print a work or class of works for a specific period) by two decrees issued from the Senate and the Doge of Venice. The ten-year privilege granted by the Senate threatened counterfeiters with fines and confiscation. (In 1496, Aldus had been granted a similar twenty-year privilege for his Greek types, and by extension his Greek books.)”*
* J. Boardley, Typographic Firsts: Adventures in Early Printing, 2019 (pp. 47, 121–23)
H. F. Brown, The Venetian Printing Press: An Historical Study Based upon Documents for the Most Part Hitherto Unpublished, 1891
J. Kostylo, ‘Commentary on Johannes of Speyer’s Venetian monopoly (1469)’, in Primary Sources on Copyright (1450-1900) eds L. Bently & M. Kretschmer, 2008, copyrighthistory.org