OP's central claim was that the bike should have been able to cover the debt, but, due to systemic malice on the bailiff's part, the bike only covered small fraction of the debt. My point is that OP is simply over-valuing the bike. If you change OP's story to: the bailiff got a decent price for the bike and took a small fee for the service, it becomes a lot less outrageous.
> [The bike] was sold at auction for £50. £35 bailiff fees for taking it there and £15 auctioneer fees, £0 off the debt.
If this claim is true, then I think most people will still find this conduct outrageous: How is it in the public interest for the baliff to take actions that harm both the debtor (by taking the personally valuable bike) and the public (by wasting from $15 to $50 of the public's money) to the benefit of only the baliff ($35) and auctioneer ($15)?
Those fees don’t seem unreasonably high to me. I wouldn’t be surprised if the bailiff was operating at a loss given the time it takes to take possession and bring the goods to auction.
It’s in the public’s interest to have mechanisms to quickly process insolvency in a way that attempts to fairly value property. Auctions solve that. If debtors don’t like the outcome, then they should sell the good themselves before it comes to that. Having others sell your property for you is always going to incur an additional cost.
The point is that, regardless of whether the bailiff’s and auctioneer’s fees are eminently reasonable, it will always result in net-negative benefit to society (excepting the bailiff and auctioneer) whenever the bailiff confiscates property whose auction proceeds are less than the sum of those fees. It is therefore contrary to the public interest for the bailiff to confiscate property unless it can reasonably be expected to substantially clear those fees when auctioned.
You just argued the bike wouldn’t have been sufficient to pay the debt. How would the owner have helped himself by selling it?