Possibility for a mower: Have you checked with neighbors on which service they use? That might work if they’re willing to just tack you on extra since they’re in the neighborhood anyway. That’s how we’ve landed landscaping services, though we use them continuously, not sporadically. And they’re legit businesses, not some random person, so they have crews and routine appointments. Like ours at two houses in different areas will email us if they’re going to change their appointment due to inclement weather, etc. They don’t just no-show. And they offer additional seasonal services, such as aeration, mosquito treatment, etc.
Also might be worth checking TaskRabbit. I’ve not used them for mowing, but the services we needed were done well. They connect you with folks who do various tasks and they’re reviewed by people who’ve hired them previously. (We’re in the U.S.)
YMMV. I’ve not encountered problems, but I screen the specific people I want to hire — those have long track records. I’ve used the same people repeatedly. They’re terrific at turning up, doing the job conscientiously. Like one of the folks I’ve hired repeatedly teaches school f/t and earns money on the side via TaskRabbit. His reviews are stellar and even the first time we worked with him, we could tell he was top notch. And he’s done way more jobs than any THS sitter I’ve heard about.