Why do you think they can ignore it? Meta has physical presence in the EU and most likely in Italy too. I doubt Meta's stock would like the Italian Government confiscating Meta's assets.

They report paying them in their audited quarterly financial statements.

My understanding is they seem to only pay them in jurisdictions where they are making enough profit to justify paying them. If Uganda for example levied these fines they’d just threaten to pull out, and would likely follow through on that.