A person who works in a coffee shop is often called a 'barista'.
Job title may be "Customer service"
assistant, vendor, teller, salesperson, salesman, floorperson.
I call them clerks or salesclerks. Also, salesperson would work.
Shop assistant.
Vendor
Mountblaze
Clerk
A florist is a person who works in a flower shop.
A mechanic
A child minder, nanny or perhaps a governess.
Client?!
Client?!
A barista
newsagent
Tech Person
a slave
Employee
Shop Assistant
Shop Assistant