You don't always need consent. There are 6 legal reasons to collect data. "Public interest" as with tax returns is one. As another example, the post office is

You don't always need consent. There are 6 legal reasons to collect data. "Public interest" as with tax returns is one. As another example, the post office is allowed to collect and process your address, since otherwise they could not fulfill their contract to deliver your parcel (contractual obligations). Similarly, paramedics don't need to worry about asking for consent from a patient that is unconscious: They can look into their medical records based on "vital interests".