Driveways and walkways need to be shoveled. It's part of what you sign on for when you buy a house. So is mowing your lawn. Your wildflower meadow is attractive to snakes & vermin. It doesn't look good. It sounds like your boyfriend wants the benefits of owning a home without doing any of the work. At the very least, talk with Tom or pay a neighborhood kid to shovel and mow when needed. If Tom knew that it would be shoveled before he got home after work, he probably wouldn't shovel at 6am.
I disagree with the first part of this. When you buy a house, within law, you get to decide what you do with it; that includes mowing the lawn and shoveling the drive. Also, it obviously does look good to some people; many are proponents of natural lawns.
I do, however, agree with the second part. If you cannot come to some sort of compromise with Tom about who does what when and how much AND you still don't want to do any of it, the least you can do is to hire someone. It is rude not to pull your weight and that is what is happening. Sure, both sides disagree on a fundamental level, but it is unfair to expect Tom to do it all just because you disagree. Try work something out with him, even if it means you exclusively shovel on the weekends and hire someone else to do it two of the other days of the week so Tom only has to do it three days himself.
If I were house hunting and there was a house on the street you described with overgrown grass and weeds, I would immediately remove the home I was looking at off my list. In fact, I wouldn't even look at the home if I hadn't seen it yet. That type of property on the street would be a deal breaker. I wouldn't want to live next to what would be an eyesore for us. While home owner can usually do what they want with their property, going so far as not to properly maintain it to the detriment of the neighbourhood or neighbour's ability to sell, that is a problem.
To be fair, I think "overgrown" may mean different things to different people. Weeds probably also mean something different to different people (I have a wildflower garden that I love, but some people would call it weeds - but in my case its in a flower bed, not the entire lawn so its clear that it is intentional-ish).
An overly manicured lawn may turn off other buyers just as much as an overgrown one (for example, I wouldn't buy a house in an area where everyone was mowing their lawn every other day to keep the grass short enough and where a single weed in the garden would look out of place - I don't have time for that and I don't want a fight with the neighborhood). So I think there is a wide range of acceptable lawn care standards and it is very possible OP and her BF are just on the other end of the spectrum from his sister and Tom.
Knee high weeds and grass covering the entire lawn and obstructing the sidewalk? Not okay. Demanding that OP and her BF trim help trim the lawn with scissors and a ruler to exactly 1.5 inches for each blade? Overly demanding and not okay. But I suspect the actual situation is something in between - which means you need to come to a house compromise on what is acceptable. Maybe that is agreeing to mow at least once a week - even if you don't think the lawn needs it. Maybe it means compensating Tom for doing your half of the yard maintenance and snow removal.
For the snow situation, I personally think it's unreasonable to insist on driving over non-shoveled snow unless there is only a little snow and its warm enough that it will all be gone by the afternoon. So I don't think leaving it until you get home from work is reasonable - especially if Tom has no way of knowing you will actually do it when you get home, only that it will be much harder for him to do it when you don't if he waits until the evening.
I also think its worth considering your own attitude towards chores. It is absolutely possible that your mom and Tom are both unreasonable in their expectations of you as an adult. But since its two separate unrelated people, it is worth considering that the problem is with your expectations as opposed to theirs. In which case, you might find that in the future you prefer living in an apartment or condo, where some chores are taken care of for you. Or perhaps budgeting for hiring outside help. And that's not a bad thing or a value judgement, just something you need to know about yourself.