Half of the things you listed you are spending WAY too much effort with voice control than non.

Sprinklers - What on earth are you voice controlling for? Just get a box on a set schedule a couple days a week, set and forget. I haven't had to think about my sprinklers for months, what advantage would I get by manually controlling them with voice or non? My water bill is so low right now that even just telling it not to run when it has rained won't save enough to make the effort worth while, and there are better non-voice controlled mechanisms for doing that anyway.

Lawn Mower and Vaccum cleaner - There are two categories of these, either autonomous (e.g. roomba) or manual. Manual ones offer no advantage for voice control because you literally just have to press a button to turn on and off, and you can visually see when it's full. Autonomous ones have no use for voice control because the whole point is they are meant to be autonomous. The only advantage I can think of is getting an alert when they need to be emptied/cleaned but that's better served by push notifications not voice queries.

Starting your car - Yes I admit this can be useful if it's cold outside so you have heat ready to go (or AC if it's hot).

Alarms & Timers - I'll give this one even though our Echo has completely failed at both of these properly, or required multiple attempts to give it the right time (at which point it was easier to just enter the timer on the microwave or stove, which we end up doing anyway).

TV (one not mentioned) - Echo has completely failed in this regard. We bought Fire TVs largely for the integration but imho it's just a complete failure. Each app has specific ways to interact with it that isn't always intuitive, if you leave off the app you want to do things on it assumes you want to look things up on Amazon's app store (e.g. "Play Chopped" vs "Play Chopped On Hulu" do very different things), the lag time prevents rewinding to be useful (I can't just say rewind 20 seconds because it usually takes 10 seconds for it to fully go back, usually missing the part I was trying to rewind to. It just became such a hassle to use voice properly that it's so much faster and reliable to use the remote. Even just pausing and playing is quicker and easier with a remote (or your phone with a chromecast) than yelling at the echo.

Music and Podcasts (another not mentioned) - This is another not mentioned that we have had some success with, but you still have to be crazy specific when making queries that it requires more mental effort than just hitting things with your phones. For example "play christmas music" makes Alexa say we have no christmas music, but "Play Christmas Music On Pandora" works and does what we want (we don't care what app is playing christmas music, we just wanted SOME type of christmas music).

Podcasts also kind of suck because its all app dependent. I can't just say "Play Johnny's house" (a local radio show) because Echo has no idea about it. I have to say "Play Johnny's house on I Heart Radio" before it works, and even then I can't give it a specific episode to play, it always plays the latest. So if I'm a day or two behind I can't just catch up.

Recipes (another not mentioned) - One great idea we had for it was to dictate recipes to us. We have never gotten this to work out while cooking and the best we have gotten was it to text a recipe to our phone, defeating the whole point.

tldr: Half of the things you mentioned make almost no sense with voice control vs the alternatives, the others are flaky enough or inconsistent enough that we (and many of our friends that have bought multiple echos) have failed to find a good use for them in the normal flow of daily life. For voice to be practical I don't want to do mental gymnastics to figure out the right way to word things and which apps I have to mention in order to have what I want to be done to be done. At that point I might as well pull out my phone or a remote and in 2-3 taps be done.