[rickboyce]

In legal systems with some basis in English Common Law the idea of an implied contract is fairly common.

Lets I buy some service from you and we sign some one-off contract. The next year I text you ‘same again please’ - you provide the same service to me. A reasonable person would conclude that there is an implied contact to provide the services under the terms perviously agreed. I can’t argue that I don’t have to pay because we didn’t sign a new set of terms.

Or you give me a quote and terms to build a house. If I let you start building it for me (and you can prove that I gave that instruction) there is an implied contract based the proposed terms even if we don’t sign any paperwork.

In the judgement here it seems to be a simpler assertion that the thumbs up in the context of asking about previously sent terms constitutes acceptance.