Especially if you consider the following factors:
As I said above, there won't be an address (or seed phrase) collision before the sun dies in ~5 billion years.
The normal user generates in his life maybe 10 addresses and not always the sum times the number of people who live in 100 years make it very unlikely.
Let's say 8 billion people all generate 1,000 new addresses every second for the next 5 billion years non stop. After 5 billion years they will only have generated 0.00000000000000009% of all possible addresses.
And I am so paranoid to trust the fewest companies.
If you don't trust any software to generate a seed phrase for you, then generate your own entropy by flipping a coin and converting each 11 bits to the corresponding word. You'll still need to use a piece of software to calculate the checksum and important the seed phrase to generate a wallet, however.