I agree with the other posters that to reduce the tips (supposedly given to servers) because of an incovenient policy is poor judgement. You should not have done that.

Also, if you were able to get cash out of an ATM, you were almost certainly able to use that card to pay the bill, making the level of inconvenience very low. Every credit union cash card I know of is also an Interac debit card.

However tips are always optional, and a reward for service. Being yelled at by a manager is poor service. If he had done that to me I would have reduced the tip to zero.

Note: It is likely that the manager was upset not so much out of concern for his staff, but because he has to make up the wages of his staff to minimum level if they don't get enough tips.