To answer your specific question as to why fonts are not copyrightable in the US, 37 C.F.R. § 202.1(e) specifies that a "typeface as typeface" is not copyrighta

To answer your specific question as to why fonts are not copyrightable in the US, 37 C.F.R. § 202.1(e) specifies that a "typeface as typeface" is not copyrightable. https://www.law.cornell.edu/cfr/text/37/202.1 https://www.law.cornell.edu/cfr/text/37/202.1