In the U.S. tap alone is used to mean selected/designated. In my opinion, it's more common here than "tap on the shoulder."
Edit: in AmE. to tap is neutral, without a connotation of favoritism or nepotism, including the use of "tap on the shoulder" in the example below about the "best teachers." I'm not familiar with the nuances of "tap on the shoulder" in BrE. and the OP's example points to a difference.
tap (v.)
SELECT, DESIGNATE
was tapped for police commissioner
specifically: to elect to membership (as in a fraternity) m-w
(usu. be tapped) informal designate or select (someone) for a
task or honor, esp. membership in an organization or committee: he
had been tapped earlier to serve in Costa Rica. New Oxford American
Dictionary
I'd voyaged from New York to Panama on the USS Gibbon when my father
was tapped to become military attache to Costa Rica. Megan
Edwards; Road from the Ashes (1999)
When Pavia and Harcourt hire her, she promised she would stay with
them for as long as she remained in private practice. Botwinik asked
that she stay at least until she was tapped to become a Supreme Court
Justice. Sylvia Mendoza; Sonia Sotomayor (2019)
But Liscouski did say the feds are looking to build a leadership team,
and he specifically wants to tap someone with industry knowledge and
business expertise to lead the still vaguely defined effort. Patricia
Keefe; "Security Disconnect" in Computerworld, July 21, 2003
Sell knew Ernie had experience, so he tapped him for the job. “One
of the reasons I brought him in,” Sell says, “was to establish
controls where there were none before.” But Ernie had little respect
for controls. Joseph Wells; Corporate Fraud Handbook (2017)
Being tapped on the shoulder [and invited into administration] is
problematic. I think it pulls the best teachers out of the classroom.
I think the best teachers are always tapped on the shoulder to
become an administrator. K. Hunter-Quartz et al.; Making a
Difference (2016)