[throwawaaarrgh]

The tool costs $100. The battery costs $100. The tools only work with the one battery, the batteries need replacing, and you need more of them to use multiple tools at once.

It is about money. Money from batteries, money from vendor lock in. This isn't cynicism, it's economics. These companies would probably lose at least half of their profit, maybe much more, if they gave up the battery.

And there's more reasons. If you want people to buy more tools (of course you do) you want to be able to phase out the old tools, and the best way to do that is a new incompatible battery. Or if you want to use a different voltage. Or if you want to ensure the battery won't set the tool on fire and cause returns or lawsuits. Or if you want to change the balance, or form factor, or something else.

[SideQuark]

I have several tools, thus several batteries, and never use them all at once. I have never in well over a decade had to replace a battery.

And even though they changed battery tech, all the tools still work with batteries in both directions. They designed each new battery tech to do that.

What tool system do you think has all the problems you listed?

[bombcar]

I’ve never bought a battery. I assume someone somewhere does, but I have enough “free” ones that will last for a long time.

[bjornasm]

So you are saying that when you are going to buy a new tool you will stick to your brand - since you have lots of batteries you can buy the discounted tool that comes without one.