Never heard of 181.fm. Will take a look.
I think that brings up an issue for online radio: nobody knows all the choices for listening online. With over the air, you have a limited number of possibilities for listening and those are known. Any online directory is comparable to the Decatur, Illinois phone book to a directory of all the phone numbers in the lower 48 states.
My point being there are so many online listening choices and no infinite directory from which to make those choices (ie: scanning the AM and FM band on a radio), the streaming station typically attracts so few listeners they cannot monetize the small number that find you.
Even if by subscription, the numbers might not be adequate to pay the costs (most likely not) and then there is sampling. You aren't not going to pay for a product you have not heard and know to be what you want to hear. The only way a person may become so loyal as to pay to listen is if they know what they are buying. That means they have to listen 'free', likely for a good while before determining they should subscribe. That sort of defeats the purpose.
Not all listeners will subscribe. Public radio touts 1 in 10 will be members. I think this is a national average, likely centering in on larger cities where public stations are more likely to hire a firm to spearhead or 'consult' their 'fundraisers'. Such firms help with on air pleas and other aspects, provide the follow-up on collections and so on. Their clients tend to do well above average. When you are a public station without such expertise, it might be more reasonable to expect 1 in 15 to become members unless you have been around decades and offer a very well researched format. Remember the rule of thumb is a fundraiser will not be successful until the 2 year mark.
In other words, the 'subscriber' might be 1 in 15 who has a history of about 2 years of 'free' listening in order to be convinced to subscribe. Will that subscriber be willing to pay a rate equal to the sum of time spent listening of 15 listeners and perhaps over time amortize the 2 years free period? If so, of total unique listeners, how many is 1 in 15? How many of that number were 'samplers', being one-time visitors that spent under 5 minutes listening to determine your station is not right for them? As the reader of this post hunting for an online listening choice, how many times do you tune away before you locate the streamer you want to listen to at that point?
Here's a sample: I selected a college streaming only station. Paying attention to programming and the station's top of mind awareness, I chose this station because they utilize the same tactics for profit rated market stations with good ratings utilize. I intentionally wanted a streaming station that could stand on it's own against competitors if on the radio dial for an example. We are talking a college station because the demographic is so tech savvy and heavy users of so called new media. Core Market: about 11,700. Unique listeners in average week (when classes are in session): 515. Average Time Spent Listening per week: 93 minutes. Average listening sessions per week: 3. Breakdown of listeners: 64% are in state (no further breakdown to determine actual in city or on campus listening); 36% listened from other states n the USA or from other countries.
When you run the above numbers, the actual number of listeners truly in the core market desired is under 330 even if every person in the state listening was actually attending this specific college (obviously logic dictates otherwise) and a total listening time each week of a mere 510.88 hours per week. It might be fair to say the number of listeners per quarter hour might be counted on both hands with fingers left over.
If the subscription was applied, 1 in 15 paying to listen, and deducting for the 'sampling' done by one time listeners who sampled once and never came back, this would mean this well programmed and well marketed station (on campus at least) might get you about 20 subscribers at best to share the expense of streaming the station. That figure would not be 'affordable' for what the subscriber gets in return, assuming that figure was breakeven divided by subscribers.
Consider if this station was universally known as an over the air station is in a certain locale, what those numbers could be. For this reason alone, I contend most listeners choose over the air streams of radio stations because that is what they are aware of simply because it is promoted via broadcast radio and other media that has a much larger listener/viewer/reader base.