Spying is intelligence collection. There many ways to collect intelligence. Some completely innocuous like going to a defense trade show and taking pictures. Or using satellites to capture imagery of sensitive locations or developments [1]. Military attaches at embassies who observe their host country’s military developments and operations [2]. These are capabilities that every developed nation has access to. For them not to use it puts them at a disadvantage.

You don’t think the French would love to have known about AUKUS submarine deal before it was made? It’s detrimental to not attempt to spy. The French were blindsided and I’m sure they don’t want to be blindsided again.

[1] https://www.space.com/arianespace-soyuz-rocket-launches-cso-...

[2] https://franceintheus.org/spip.php?article10460