police consider anyone who doesn’t provide info as obstructing justice.
That is incorrect.
If the police ask you what you saw and you say nothing, even when they know full well you saw it, there is nothing they can do. You're not obstructing justice. You're simply refusing to testify. You could still be subpoenaed to testify before a grand jury if they had sufficient probable cause to believe your testimony under oath would be worthwhile.
Obstruction of justice is when you TAKE ACTION to prevent the discovery of a criminal act. For instance, you hide material evidence or give false testimony (such as an alibi for someone that isn't true).
President Trump is guilty of obstruction of justice with ease. He not only attempted to coerce the head of the FBI into "letting it go" and "removing the cloud", he fired him when that director refused to do so. He did that with the sole purpose of derailing the investigation into the matter.
That is the textbook definition of obstruction.