Not all places. Those that are not chain stores. The Mom & Pop nursery where the owners are in the business because they are gardeners and have been doing it a long time. Commercial chains turn over stuff or throw it out because if nobody bought it last season it just becomes a burden and it costs money to store and move it from here to there and it costs more to move it around next season and it costs to have an employee clean it up and it's not standard looking anymore. They only handle standard merchandise that has a predictable turnover so they don't carry the unusual cultivars either. It's cheaper to throw it in the dumpster, or mark it down low enough for someone to carry it away and write off the difference than to handle it again, and again. There's a standard dollar amount allotted for handling goods and every time an employee has to touch it again, that cost comes out of the bottom line. Never handle anything twice. That's good business.
But the old Mom & Pop family business doesn't operate that way. They will buy some stuff every year that's not ordinary in the trade just because they like interesting cultivars, like J. chinensis 'Parsonii', if that's what it is. If it doesn't sell, they'll put it out of sight and leave it there for years. They'll eventually sell it to someone like you. Or me. When you're out and about, keep your eye open for that nursery that's not on a main thoroughfare, that's been there a long time, age-worn, ~out of date~, small-ish. And when they ask what you're looking for, tell them. They'll probably make you pay more than market value, like the OP, but you'll get the better part of the deal.