Sale contract based on Bai Muaatah...using word but no contracts signed between two parties. Is it Permissible in Islam? What is the example of the contract?

1. A contract of sale (ba'i) in which the buyer picks up the goods
and pays the price to the seller who accepts it without both
parties sitting down to draw up a contract. This is the case where
retail trade comes into play. For example, in a supermarket, a
customer would proceed to choose a specific article (say
toothpaste) and then pays its price at a point of sale (POS) and
simply leaves. However, ba’i al-mu'atah doesn’t fit into cases
involving the sale or purchase of valuable items such as a real
estate property or a vehicle, as the seller and buyer would
normally have to formulate an official contract in which transfer
of ownership shall be reduced into writing.
Ba'i al-mu'atah is also termed ba’i al-ta'ati. Both ta’ati and
mu’atah are Arabic words which denote an action taking place
and coming into effect by virtue of the implicit approval of both
parties and without resorting to formalities (such as
documentation). In other words, ba’i al-ta’ati or al-mu’atah it is
a contract that is effectuated based on physical action (grabbing
of an item, payment of price by the buyer and receipt by the
seller) rather than verbal offer and acceptance.
It is also spelled bai’ul mu'atah.