a temperature check is not a medical diagnoses for you.
its a safety check for everyone else.

what you will find is that when people are in a store. if they are injured/harmed in that establishment due to something that can be prevented by the shop owner. the shop owner becomes liable for that harm. especially if the shop owner knows about the harm

its why there are 'caution slippery floor' signs and shops are suppose to be at a certain light level and temperature.

right now in the UK schools are in uproar where government want kids to go to school because covid is not a health risk to the kids. but is not helping much with the safety of teachers and parents when kids mingle and pass it around.
teachers want to be provided with face masks and gloves and aprons as a minimum. but the government say it should be just wash all surfaces and hands policy. unless someone is symptomatic.

.. i digressed
a shop owner has to keep himself and his business and other customers safe. and having a temperature check is not much of a impact to a persons day.
id actually be happy if a shop owner kicks out someone thats overtly sweating and coughing over the fruit

..
atleast its not like WW2 rationing. where you were given vouchers to do your shop and only able to buy certain produce. and only on certain days,