The issue is that a lot of smaller deals fall through, either because of unrealistic final price expectations by the seller or because some metric that is super important to the business was calculated and supplied in the wrong way (i.e. churn). Or there are issues in structuring the contract because the seller (or his legal advisor) "overengineers" the contract -- lawyers can and sometimes do end up killing deals.
As a buyer, if I pay you a $25k fee, you now have leverage over me. Because if the deal doesn't happen I'm out $25k. If I don't pay you anything you're incentivized to get the deal done and try and draft a balanced sale/purchase agreement that works for seller and buyer. That means both parties making concessions on terms. In my mind, that is healthy, because if we finalise the deal you're getting a bag of money.
Let's say there is a clause we just can't find each other on. No worries, we can jointly decide to walk away. If I paid you and you're not willing to budge, then I'm out $25k if I walk away. It doesn't keep the discussion balanced.
Add to that that some people might (in the end) be unsure whether they even want to sell or not, and you end up in a situation where it's all mostly uncertainty (for both parties) until the deal closes.
Balanced? Utter nonsense and I suspect you know it. You know that proceeding past an LOI involves the seller accruing costs, sinking massive amounts of time on activities other than working on their business, and, more often than not, becoming emotionally invested in 'doing the deal'. Buyers buy businesses a lot more frequently than sellers sell businesses, and that makes the transaction a "home game" for the buyer, giving buyers an advantage.
Not providing any earnest money minimizes buyer risk, allows buyers an opportunity for a cheap education on the ins and outs of a successful business, and invites other tactics to tilt negotiations away from the seller - all the reasons selling a business becomes one of the most painful experiences of an entrepreneur's professional life.
If you're not prepared to provide any earnest money, you probably haven't done enough work to decide whether you're really entering into an LOI. Hopefully, the sellers negotiating with buyers like you figure that out and push back.