I do not understand what you're trying to communicate with "hold by a string" - we subsidize our farmers because we do not want to completely wreck our local agricultural supply chains just because food from, say Brazil, would be theoretically cheaper today. Another factor is that we actually have the ability to properly enforce quality standards if the food is produced within our jurisdiction.

This is no different to subsidizing public transport, because having this infrastructure local and autonomous is just strategically important enough for the tax payer to finance it. Would you say that public transport in EU capitals is "holding on by a string"?