It's hard because developers don't usually have spending authority or budget. Often, nor does their manager or their manager's manager. To get the company to buy something you have to escalate to an absurdly high place in the org chart and so devs will often try to cobble something together out of free stuff, even if it's far less efficient, because spending developer time doesn't require permission whereas spending credit card balance does.

Unrelatedly, there's also to some extent an expectation that everything is free, even for commercial users. The most common pricing question I get about my product is "can't you make it free for commercial projects that don't have revenue yet", i.e. effectively asking me to become investors in their own venture. Because often they want to make a product company, but not spend any money to do so.

Source: I run a small software company that sells to developers.