While I am not as old as John Timpson the chairman of Timpson, I understand his annoyance at being called mate in a store. You can read what he said here :

https://www.telegraph.co.uk/business/2021/10/11/getting-matey-customer-not-always-best-approach/

I also do not like to be called mate or chum or even bruv. However, I put this irritation behind me for two reasons.

First, I am getting served and served well by the people who use these terms.

Secondly, I do not reflect the preferences and opinions of most people who now shop, so I should really keep quiet.

I put all this aside in support of the fact that while UK store staff may not be the most professional, efficient or formal in their communications with customers, they do excel at making a personal connection. An exchange in a UK store often becomes a nice chat among equals, each sharing their frustrations about Brexit, Johnson, lorry drivers, fuel shortages etc. This is then backed up, most of the time, by a willingness to help me out, solve my problem and go just that little bit further to find what I am looking for.

The same cannot be said of many countries in Europe. In the US, service is highly professionalised but it is not personal. In some countries, service is non-existent. So Mr Timpson, while I share your dislike of these familiar terms of address, I will put up with them so I can carry on getting great service.

For what it’s worth, and perhaps this is a cheap shot, but I’ve never thought much to the service in Timpson outlets, not friendly at all.