Outdoor AV is, of course, targeted at those who are likely to spend more leisure time outdoors in their garden. This implies a favorable climate, so interest in this type of product is likely to be can be heavily reliant on where people live.
Anyone with a garden that closely adjoins that of neighbors is going to be unpopular if they install such AV. This therefore plays in to the CEDIA market — relatively high-wealth homes with large gardens in a good climate.
Check out John Sciacca's review of the NEAR NEARScapes IG44.1 DSP Outdoor Audio System
The solutions being offered are becoming higher end (e.g., soundbars, 4K UHD TVs), so brands believe this is a market worth targeting.
The U.S. is fertile ground for this type of product as it has a highly developed custom installation channel that can recommend, supply, and install this type of product as part of broader installation project — for example, an outdoor lighting security installation could be upsold to include outdoor AV.