It's perhaps developer of altcoin wallet wanted to make money simply as that. So most of them are closed source and you don't have total control of the fees because that's where they are going to make money from us.
Unlike Bitcoin like Electrum, which is open source and it has built it's reputation already.
OMG... wallets with closed source code usually raise a lot of suspicion, but that doesn't mean they openly have bad intentions to take advantage of their users through illegal things... we can't judge that directly....
I don't like and am not interested in using wallets with closed source code, but I've used them for some time and there were no problems at all... I've never lost my balance when storing in a closed source wallet... but in an open source wallet, I actually experienced hacking...
And for Electrum which doesn't make an altcoin wallet, the first thing that comes to my mind is the complexity of the altcoin wallet which makes it no longer simple... I still love Electrum which can only store BTC like it is now.