Ok, so you're asking about a different point, now, the difficulty of paying. In that case the difficulties arise because of corporate gatekeepers, licensing stewards and general policies governing software licensing. Typically my organisation would not approve this sort of purchase without a business case and justification - not least because we are a not-for-profit and any money not going to our cause is scrutinised heavily (the thing donors absolutely hate the most is the idea their money doesn't get to the cause they donated to and instead goes into sinkhole of funding commerical company's bottom lines).
Obviously one payment is not too big but as soon as the policy allows one it allows all such things so its effectively opening the gate to all kinds of micro-payments that quickly build up and become entrenched as "essential".
Here's a similar analogy ... does your company pay for your parking? Why not, its small compared to your salary right? and it definitely helps you get to work, be more efficient etc? Well its not just about the parking its because that represents a class of purchase that if allowed would tilt the scale towards a massive number of similar types of expenses. So in fact most places will have blanked policies disallowing small purchases.
Another question: since the price for Docker Desktop already got arbitrarily changed with no notice, why would you believe that it won't go up in the future? Or get more restrictive in other ways? Once a company executes bad faith one time, continued manifestations of that have to be considered as a risk.