For example, you can't prove a transaction really compared to normal coins like Bitcoin and Ethereum.
You can, see
How to prove you've made a payment. But maybe you mean that you can't prove "someone" made a transaction if this "someone" is not you (or doesn't provide you the tx key), and in this case you're probably correct.
However: is this enough to make it "more difficult" to use? Who would need to prove that someone made a payment, if he's neither the sender nor the receiver?
Sending and receiving coins with XMR is as easy as with all other coins (although the addresses are quite long, but that doesn't make much of a difference for me).
In addition, Monero is a DarkNet coin and we can suffer from crime and scam more easily because also Monero is also more difficult compared to normal coins like Bitcoin and Ethereum.
I don't see how. In general I think coins like Ethereum with all the possibilities turing-complete smart contracts provide are much more prone to scams. On Ethereum those selling you a token can even freeze it at all times and you won't be able to sell or use it anymore. You can of course check the Solidity code, but how many people do that?
I don't know really much about Monero.
Very early, I tried to collect some Monero Coins for free from a faucet, where I have created a Monero address but it did not work and I did no additional research after it.
It just seemed way to difficult for when I tried to find out.
And it turned out sticking to Bitcoin was more profitable because when I've tried to collect Monero coins, a Monero Coin was at 120 USD and a Bitcoin was at 10k USD and today, a Monero Coin is still at 120 USD but a Bitcoin is at 50k USD.